The Foxtrot Mike Products FM-9 Complete 9x19mm Upper Receiver is feature rich and cutting edge. Built from the ground up to provide outstanding reliability and accuracy with a host of top tier features. The traditional M4 charging handle has been replaced with an ambidextrous, non reciprocating forward charging handle. The monolithic style has been achieved with a proprietary interlock between the upper and handguard. Lastly, the slim-line handguard is M-LOK compatible for your favorite accessories.