This is a Timney Triggers Safety Selector known as the 49'er, model AR49ERSAFETY.
The Timney 49er 49 or 90 DEGREE SAFETY (Ambidextrous) can be used in either the normal 90 degree or for ultra quick changes a 49 degree short throw for quick and easy manipulation. In addition" the safety features an end plate allowing the removal of the ambidextrous arm if a one-sided safety is preferred. The 49'r is a true drop-in part that will work with any Mil-Spec lower receiver.
Features:
Precision Machined
Heat Treated Steel
49-Degree Throw
Faster Safety Manipulation