This 30 round AR-15 magazine from Elite Tactical Systems or ETS is made of translucent polymer. This advanced polymer is impact and chemical resistant, also holds up well to heat, cold and UV rays allowing it to not become brittle or yellow over time. The translucent body allows the shooter to see round count and ammo type. The built-in coupler allows multiple mags to be connected together in seconds with no tools or extra parts. Other features include a non tilt follower and dust cover to keep dirt and debris out. This AR magazine supports 5.56, .223, and 300BLK rounds.