Timney trigger ar-15 3lb pull solid straight small pin FEATURES:-Material Steel/Aluminum-Will fit most AR-15 Rifles3lbs pull-Self contained unit-Uses the same hammer and trigger pins Other Features: 3 lbs pull non adjustable solid straight trigger small pin model (.156" pin) will fit most ar-15 rifles small pin fits almost all ar15 a few colt ar's use the large.176" pins all other ar-15's use the.156 trigger pins which is mil-spec