Drop-in triggers are an easy upgrade that can take an AR from okay to exceptional, though mil-spec style trigger pins can have a tendency to "walkout of one side of the receiver while firing, especially with cassette style trigger packs.CMMG ZEROED Anti-Walk Trigger Pins come with everything you need to solve that dilemma including: (2) trigger pins and (4) Torx T8 trigger pin screwsFits .154diameter pin AR receivers.