Dust caps

check some Top Best Paintball Guns 2021 you'll find great paintball.

I use those as well...very well made fit perfectly over foster adapter with ball bearings inside.

I've been using, and happy with, the magnetic caps from Ninja Paintball (available on Amazon). There have been a couple times when I thought they'd 'come off' on their own, but then I find them next to my fill station, indicating that I forgot to replace them. Haven't lost one in the field yet.

GsT