This set contains parts needed to attain specific trigger pull weights for a 1911. These parts are heat treated to RC 42-44 and designed for trigger pulls of 4 lb and greater. Perfect for tactical or match use. Factory replacement parts are manufactured to the exact same specifications and tolerances and use the same manufacturing materials as the original parts. Requires fitting and installation by a qualified gunsmith. Springs have been prepped and matched at the factory. NoteKit includes tactical hammer, tactical sear, and match disconnecter