This is a Angstadt Arms Buffer known as the 9mm, model AA09BUFKIT.
The Angstadt Arms 9mm buffer assembly kit is compatible with both GLOCK(R) and Colt(R) style 9mm AR-15's. Weighing 5.4oz" this buffer is tough enough to withstand the abuse of blowback 9mm firearms and features a dedicated buffer spacer to limit overtravel of your 9mm bolt carrier. Includes 9mm buffer" spacer and carbine buffer spring.
Features:
• Complete drop-in 9mm AR-15 buffer kit
• 5.4oz buffer weight
• Includes buffer, buffer spacer and carbine spring
