Small parts you wanna keep on hand - AT3 Tactical FU-BAG AR-15 Lost Parts Kit

I keep a few of these around, in my range bag, in my EDC bag, and in a pouch on my battle belt. You never want to have your rifle go down while in use, from a broken spring or fly-away detent, and these replacement parts along with trigger springs and a spare bolt are sure to keep you up and gunning. Also handy for new builds, especially when you're building a mutt, custom down to the pivot pins and adjustable gas block.