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
$290.00 inc. GST
Apeks RK4 Fins use a compact, wide rubber blade for controlled scuba finning.
- One-piece rubber construction.
- Adjustable stainless-steel spring straps.
- Integrated strap buckles.
- Large rubber pull tabs for use with gloves.
Designed for use with suitable wetsuit or drysuit boots. Choose the fin size with your intended boots.
SKU:
- Description
- Additional information
- Shipping
- Returns & Exchanges
- Click & Collect
- Frequently Asked Questions
Apeks RK4 Fins – Technical Scuba Diving Fins
Move confidently underwater with the Apeks RK4 Fins, combining a compact, wide blade with precise control and efficient propulsion. Designed for technical and recreational scuba diving, these rubber fins deliver excellent manoeuvrability in confined spaces and dependable performance in open water.
Ideal for frog kicks, back-finning and small positional adjustments, the RK4 helps you control your movement around reefs, wrecks and overhead environments. Used with appropriate finning techniques, the compact blade helps minimise sand and silt disturbance, preserving visibility.
Adjustable stainless steel spring straps accommodate wetsuit and drysuit boots, while integrated buckles reduce snag points. Oversized rubber pull tabs make putting on and removing your fins straightforward, even with gloves.
Features and Benefits
- Compact, wide blade: Provides controlled propulsion and excellent manoeuvrability when space is limited.
- Precise fin control: Well suited to frog-kicking, back-finning and fine adjustments to your position underwater.
- Efficient propulsion: Designed to deliver useful thrust on both the upstroke and downstroke, helping conserve energy throughout your dive.
- Reduced silt disturbance: Supports controlled finning techniques that help keep sand and sediment undisturbed.
- Adjustable spring straps: Stainless steel straps feature two adjustment points to help accommodate different wetsuit and drysuit boots.
- Integrated stainless steel buckles: Tough, durable hardware keeps the strap attachment streamlined to reduce snag hazards.
- Oversized rubber pull tabs: Easy to grip when wearing gloves, making the fins easier to put on and take off.
- One-piece rubber construction: Provides durability for regular use in demanding diving environments.
Whether you are refining your technical diving skills or looking for greater control on recreational dives, the Apeks RK4 technical fins combine accurate handling, practical adjustment and lasting durability.
Choosing your RK4 size
Choose your fins with the dive boots and socks you will use. Boot brand, type, neoprene thickness, sole thickness and overall shape can affect the correct fin size. Boots with the same labelled shoe size may fit differently in the pocket. Open the RK4 Size & Fit Guide above for fitting checks and measuring advice.
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. |
Available colours: Black, Grey, White and Orange.
Fit advice: These fins require suitable dive boots. Choose your fin size with your actual wetsuit or drysuit boots in mind, as boot thickness and design affect the fit.
| Colour | Black, Orange, White, Grey |
|---|---|
| Size | Small, Medium, Large, XLarge |
We dispatch orders five days a week, usually within 1–3 days. 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.
We offer a 30-day exchange on most unused products within Australia when they are in saleable condition with their original packaging and accessories. Please contact us with your order number before returning an item. Change-of-mind refunds are not offered; this does not limit your rights for faulty products under Australian Consumer Law.
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.
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. If you are unsure, contact our team before ordering and we can help you choose.
How do I check availability?
Select your required options, such as colour and size, to see availability for that variation. If an item is marked “Available to order”, check the estimated dispatch information. Please contact us before ordering if you need gear by a particular date.
When will my order be dispatched?
Orders are usually dispatched within 1–3 days, subject to stock availability. Available-to-order and special-order products may take longer. 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?
We offer a 30-day exchange policy on most unused products within Australia, subject to eligibility. Contact us with your order number before returning an item. Read the exchange 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.
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