UAC Match Grade Steel Hammer & Sear Set is constructed by precision CNC with carbon steel. The tight tolerance ensure the hammer & sear are in perfect shape. No burr is left behind, so no modify are needed. Also, titanium nitride (TiN) coating is used on the finishing to reduce the galling and friction. This is the most professional hammer & sear set ever made for airsoft TM G17 and perfect for competition.