Agreed, but there is no easy solution on how to attach the cap to the Custom Divers canister. The cap is also about 50% the size of the canister. So if after getting the PLB1 out and clipped to me, I lost the canister, the cap is just as good of a cup.Having both the canister & cap tethered to you is also important. If you open the canister while floating on the surface, wave hit you and you lose grip of the canister, you don’t have to swim and search for it, just pull the line back to you.
EDIT: Hrm, now that I think about it, I should drill a similar hole on the bottom of the canister like there is on the cap. Then I could just pass the cave line through both holes and it would work perfectly. Just need to get the nerve up to drill the hole...