Anderson Manufacturing. The trigger & Hammer are stainless steel.
This is a very good quality Lower parts Kit. FYI: These are difficult to order, and takes months to get.
Complete Lower Parts Kit includes, Bolt Catch, Bolt Catch Plunger, Bolt
Catch Roll Pin, Bolt Catch Spring, Buffer, Retainer, Buffer Retainer
Spring, Disconnect, Disconnect Spring, Stainless steel Hammer, Hammer Pin, Hammer Spring, Magazine Catch, Magazine Catch
Button, Magazine Catch Spring, Pistol Grip (A2 style), Pistol Grip Lock
Washer, Pistol Grip Screw, Pivot Pin, Pivot Pin Detent, Pivot Pin Detent
Spring, Selector, Selector Detent, Selector Detent Spring, Takedown
Pin, Takedown Pin Detent, Takedown Pin, Detent Spring,
Stainless Steel Trigger, Trigger Guard, Trigger Guard Roll Pin, Trigger
Pin, Trigger Spring.