For octos, you have two options. You could buy a traditional yellow hose octopus that attaches to your second stage (of which we have several) or you can check out the Seaquest AirSource
which is the integrated octo that fits on this BCD. The "Wenoka Squeeze Lock" knife is very nice and attches great to seaquest BCDs. We carry the knife with three different tips; tanto, stilleto and blunt.