Apeks RK4 Fins Size & Fit Guide
Choose your RK4 fins with the dive boots you will wear. Dive boot brand, type, neoprene thickness, sole thickness and overall shape can all affect the correct fin size. Boots with the same labelled shoe size can fit differently in the fin pocket.
The table shows RK4 foot-pocket dimensions in centimetres. These are measurements of the fin pocket, not recommended bare-foot lengths or shoe-size ranges. They are a reference only and do not guarantee that a particular boot will fit.
Choosing your size
- Small: Contact us for sizing advice. Foot-pocket measurements are not available for this size.
- Wetsuit boots: Take account of neoprene thickness, sole thickness, toe shape and the height of your instep.
- Drysuit boots and rock boots: Try the fins with the complete boot and sock combination you will use. A bulkier boot can change the size you need.
- Changing boots: Recheck the fit if you change boot brand, style, thickness or socks. Do not assume your RK3 size will be your best RK4 size.
Check the fit before diving
- Try both fins on with your intended boots and any socks or underlayers.
- Your boot should sit securely and comfortably in the pocket, without forcing it in, squeezing the toes or pressing painfully over the instep.
- Use the RK4 spring-strap adjustment points to achieve comfortable heel tension. Strap adjustment cannot make a foot pocket that is too small fit correctly.
- Check that your heel stays secure and the boot does not slide around or pull out easily. There should be no numbness, pain or excessive strap pressure.
Boots and sock advice
Dive boots must be worn with these open-heel scuba fins. Suitable boots help protect your feet when entering and leaving the water. Lycra fin socks worn inside your boots can help reduce rubbing and make boots and a wetsuit easier to put on; include them when checking your fin fit.
How to measure your feet
For help choosing your dive boots, stand on paper with your heel gently against a wall. Mark the end of your longest toe and measure from the wall to that mark. Measure both feet and use the longer measurement with the boot brand’s own size chart. Do not match this bare-foot measurement directly to the fin-pocket depth.
Need help choosing?
Tell us your boot brand and model, labelled size, neoprene thickness, whether you use wetsuit or drysuit boots, and any socks or underlayers. Visit our Hallam store for a fitting, call 03 9702 3694 or email [email protected].
| RK4 fin size | Pocket depth (cm) | Pocket width (cm) |
|---|---|---|
|
Small (S)
|
Contact us
|
Contact us
|
|
Medium (M)
|
22
|
9
|
|
Large (L)
|
25.5
|
9.5
|
|
Extra Large (XL)
|
27
|
10
|
Apeks RK4 Technical Diving Fins
$300.00 inc. GST
Apeks RK4 fins pair a compact, wide rubber blade with adjustable stainless-steel spring straps for controlled scuba finning. Well suited to frog kicks, back finning and fine position changes, they feature integrated buckles and large pull tabs for gloved handling. Choose the size with your actual wetsuit or drysuit boots; boots are sold separately.
SKU:
- Description
- Additional information
- Shipping
- Returns & Exchanges
- Click & Collect
- Frequently Asked Questions
- Reviews (0)
The Apeks RK4 fins give scuba divers a compact, wide rubber blade for deliberate, controlled movement. They suit recreational and technical divers who use frog kicks, back finning and small position changes to manage their distance from a reef, wreck or dive buddy.
The open-heel foot pocket works with suitable dive boots, while adjustable stainless-steel spring straps make it easier to set up the fit around your chosen footwear. If precise handling matters more to you than a long blade, the RK4 is worth trying with your own boots.
Features and benefits
Compact, wide blade for precise finning
The short, broad blade lets you make small corrections without needing a large leg movement. This is useful when lining up a photograph, holding position beside your buddy or practising frog kicks and back finning. Careful technique can also help limit sediment disturbance; fin design alone does not prevent silting.
Thrust on both parts of the kick
The blade is designed to provide propulsion on the upstroke and downstroke. You can use both parts of the movement to maintain progress, while adapting your kick to the space and conditions around you.
One-piece rubber construction
The blade and foot pocket form a one-piece rubber fin. This gives the RK4 a straightforward construction for regular diving, with a compact blade that is easy to inspect when you rinse your equipment after a dive.
Adjustable stainless-steel spring straps
Two strap adjustment points help you accommodate different wetsuit or drysuit boots. The spring strap holds the heel in place without a conventional adjustable rubber fin strap, while the large rubber pull tab gives gloved fingers something substantial to grip when putting the fins on or taking them off.
Integrated stainless-steel buckles
The strap attachments sit close to the fin to reduce protruding snag points. This is a practical detail when managing hoses and other equipment, although you still need to keep your configuration tidy and check the surrounding area before moving.
Choosing your RK4 size
The RK4 has a snug foot pocket intended to hold a dive boot securely. A good fit should feel stable without pinching or requiring excessive strap tension.
Try the fins in-store with the boots and socks you plan to use. Boot brand, shape, neoprene thickness and sole design all affect the fit, even when the labelled shoe size is the same. Open the RK4 Size & Fit Guide above for the fitting checks and measuring advice.
Foot-pocket measurements below are references for the fin itself, not recommended bare-foot lengths or guaranteed shoe-size ranges. Suitable dive boots are required and are sold separately.
What’s included
A pair of Apeks RK4 fins with fitted spring straps and a user manual. Choose from the available Black, White and Orange options, then select the size that works with your diving boots.
Care and storage
Rinse the fins in fresh water after diving to remove salt, sand and other debris, paying attention to the foot pockets, straps and buckles. Allow them to dry out of direct sunlight, then store them in a cool, dry place without bending or loading the blades.
Before your next dive, inspect the rubber, blade edges, spring straps and attachment points for damage or looseness. Replace worn or damaged parts before use. Clean your dive boots separately according to their care instructions.
Technical Specs
| Fin model | Apeks RK4 |
|---|---|
| Foot pocket style | Open heel |
| Designed for | Recreational and technical scuba diving, including frog kicking and back finning |
| Construction | One-piece rubber construction |
| Blade material | Rubber |
| Blade design | Compact, wide technical blade |
| Foot pocket material | Rubber |
| Strap type | Stainless-steel spring straps with two adjustment points |
| Buckles | Integrated stainless-steel buckles |
| Footwear | Dive boots required; suitable wetsuit or drysuit boots |
| Available sizes | Small (S), Medium (M), Large (L), Extra Large (XL) |
| Small foot pocket — depth × width | Contact us for sizing advice; measurements are not available |
| Medium foot pocket — depth × width | 22 × 9 cm |
| Large foot pocket — depth × width | 25.5 × 9.5 cm |
| Extra Large foot pocket — depth × width | 27 × 10 cm |
| Boot fit guidance | Boot brand, type, neoprene thickness, sole thickness and overall shape affect fit. Try the fins with your intended boots and socks. |
| Measurement guidance | Foot-pocket dimensions are a reference only. They are not recommended bare-foot lengths or shoe-size ranges and do not guarantee that a particular boot will fit. |
Ready to choose your RK4 fins? Select your colour and size above, or ask Dive Gear Australia for help checking the fit with your boots. You can also browse our scuba diving fins to compare the range.
| Colour | Black, Orange, White |
|---|---|
| Size | Small, Medium, Large, XLarge |
In-stock orders placed before 12 noon Melbourne time on weekdays are usually dispatched the same day once payment is confirmed. This excludes public holidays, pre-orders, backorders, special orders and custom orders. Dispatch times can vary. Delivery time depends on the carrier and your location.
Standard mainland Australian shipping is $20. Click & Collect from our Hallam store is free once your order is ready.
- Large or bulky gear: additional freight charges apply on top of standard shipping: large dive bags $30; long freediving fins $15; long spearguns $20. Scuba tank freight is shown at checkout.
- Rural, remote & offshore: rural means anywhere outside metropolitan areas. Carrier availability and additional charges may apply, including for island and territory destinations. Our team will contact you if an extra freight quote is needed.
The available delivery rate for your order is shown at checkout.
Need your gear urgently? You are welcome to arrange your own same-day courier or Uber pickup from Hallam. Call 03 9702 3694 before booking so we can confirm payment, that your order is packed and ready, and a collection time. Tell us who will collect and give your driver the order number. You arrange and pay the courier directly; delivery timing depends on the provider.
Contact us within 30 days of delivery to request a refund, exchange or optional store credit on eligible unused goods within Australia. Refunds go to the original payment method. Keep goods clean and undamaged with tags, original packaging and all accessories. No restocking fee applies to eligible returns meeting these conditions.
For change-of-mind returns and size exchanges, you pay return postage and replacement shipping. Original delivery charges are not refunded. Water-tested goods, clearly marked clearance items and genuinely custom-made or personalised items are excluded from change-of-mind returns. Ordinary discounted goods remain eligible.
For product problems, please call 03 9702 3694 before returning an item so we can help and explain the next steps.
Still unsure which size to choose?
Call our experienced dive instructors on 03 9702 3694 before ordering. Have your measurements and preferred product ready so we can help you choose the most suitable size. Fit varies between brands and models.
FREE CLICK & COLLECT
Usually ready same day*
Select local pickup at checkout. We will email you when your order is ready. Please wait for your ready-to-collect confirmation before visiting, then bring your confirmation email and photo ID.
Need your gear urgently? You can arrange your own same-day courier or Uber pickup. Call 03 9702 3694 before booking so we can confirm payment, that your order is packed and ready, and a collection time. Tell us who will collect and give your driver the order number. You arrange and pay the courier directly; delivery timing depends on the provider.
Collect from our Hallam store
Factory 4 / 56–60 Hallam South Rd
Hallam VIC 3803
*For items in stock at our Hallam store during opening hours, subject to order processing. Available-to-order and special-order items take longer. Collection is unavailable while the store is closed.
Can I collect my order from the store?
Yes. Choose free local pickup at checkout and wait for your ready-to-collect email before visiting our Hallam store. Bring your confirmation and photo ID. See Click & Collect details.
How do I choose the right size?
Use the product's size chart where available and compare your measurements with the guide for that brand. Sizing varies between brands and products. Still unsure? Call our experienced dive instructors on 03 9702 3694 during business hours before ordering. Have your measurements and preferred product ready. For fins and boots, tell us which socks or dive boots you will wear.
How do I check availability?
Select your required options, such as colour and size, to see availability for that variation. “Available to order” means the item may need to be sourced before dispatch. Call 03 9702 3694 to check the current lead time before ordering, especially if you need your gear for a trip or a particular date.
When will my order be dispatched?
In-stock orders placed before 12 noon Melbourne time on weekdays are usually dispatched the same day once payment is confirmed. This excludes public holidays, pre-orders, backorders, special orders and custom orders. Dispatch times can vary. Delivery time is separate from dispatch time and depends on your location and the carrier. Read our shipping information.
Can I exchange an item if it does not fit?
Contact us within 30 days of delivery to request a refund to the original payment method, exchange or optional store credit on eligible unused goods. You pay change-of-mind return postage and replacement shipping; original delivery charges are not refunded. No restocking fee applies to eligible returns. Clearance and genuinely custom-made items are excluded from change-of-mind returns. Read the return conditions and next steps.
Can you help me choose the right gear?
Yes. Call 03 9702 3694 during store hours or email [email protected]. Tell us which product you are considering and how you plan to use it.
Only logged in customers who have purchased this product may leave a review.
Similar products
View all Open Heels Fins
Reviews
There are no reviews yet.