Oceanic Tank Band Weight Pocket Pair
These Oceanic pockets attach at a compatible cylinder band to carry trim weight closer to the tank. The listing is for a pair of non-ditchable pockets.
Weight placement
Check the fit of the pockets on your tank band and recheck your trim and total weighting after fitting. These are fixed trim-weight pockets; keep ditchable weight in an appropriate release system as your dive plan requires.

HQ Diving 2.5kg Quick-Release Scuba Trim Weight Pocket
Atomic Aquatics BC2 BCD Accessory Pocket 