Keep things simple when diving with/around others. Also nice backup in case of sticky fingers of passersby. Cheap, good.

Put initials on a bunch of stuff from neoprene to plastic and wood. So far so good. Thought it would rub off pretty quick on the booties but not yet.

I mark all my small items like booties, gloves, lanyards and bags with this as well as my wetsuits. It does not stay on things like snorkels and masks. It peels off after a while. I also put it on my dive computer. I run a bead between the strap and body underneath. So when there's 6 DF4s on the boat I know which one is mine.