any ole' barrel plug will do, but right now i'm using an empire barrel condom
i bought this because it was really cheap. i think i paid like $5 or less for it. it's not even worth the lincoln that i paid for it. after using it for 2 days, it already had a huge gaping hole in it. i asked my friend to hold my gun for me, and he accidentally nudged my hair-trigger and sent about 2-3 balls into the barrel condom. it ripped and the hole was about 3-4 finger widths. i will never buy ronin gear ever again. i only bought their gear because the guys that work at the stores are nice, but ronin gear sucks beyond belief
good- has a clear plastic window for you to put your i.d. for scenario games i suppose
bad- ripped after 2 days' use. pain in the rear to clip the thing around the feedneck, trigger frame, loader, etc. big and cumbersome. ugly. ronin gear
do not under any circumstances ever buy this product. it is not made well, and the whole point in having a BBD (barrel blocking device) is so that if you accidentally pull the trigger with it on, it won't let the paintball come out of your barrel or hit anybody nearby. i have serious safety issues with this product, and so i'm giving it the lowest rating possible.