Badger Ordnance Universal Reversible (ambi?) Safety Selector

Okay, not really ambi, but reversible, to be used for LH or RH use.

The Badger Ordnance Universal Safety is a replacement for your standard AR-15 safety. The Universal Safety can be installed in a right hand or left hand configuration. The safety is marked with high visibility paint and the off-hand side is raised for visual and tactile indication of the safety's position. Machined from billet 4140 hardened steel and finished in a mil-spec Parkerizing. 

Part 249-42