Rainier Arms Gen 2 Forged A4 Upper Receiver AR-15 Black. These uppers are "T - marked" engraved and have extended M4 feed ramps. Gen 2 Uppers are deep black finish and match well with RA lowers and MEGA lowers Specifications for Rainier Arms AR-15 Gen 2 Forged A4 Upper Receiver: Manufacturer: Rainier Arms Color: Black Gun Make: AR Platform Gun Model: AR-15 Included Accessories: Standard Condition: New Package Contents: Rainier Arms AR-15 Gen 2 Forged A4 Upper Receiver What firearm models does the manufacturer say Rainier Arms AR-15 Gen 2 Forged A4 Upper Receiver is compatible with? The manufacturer suggests that Rainier Arms AR-15 Gen 2 Forged A4 Upper Receiver is compatible with AR-15Rainier Arms RA-A4-UR-G2: Gen 2 Forged A4 Upper Receiver AR-15 Black