A device used to remotely release fish suffering from barotrauma at a safe depth. Get a free descender here: https://oceaned.org/request-devices/
Nice selection of options. I gave a donation in exchange for decender from that website, and the wire device they sent me was much cheaper quality than the ones you have there. I use a down rigger for descending big groupers, even with 6lbs of lead, they sink back down slowly.