The Foxtrot Mike Products FM-45 Complete .45 Cal Upper Receiver is built from the ground up to provide outstandingreliability and accuracy with a host of top tier features. The traditional M4 charging handle has been replaced with anambidextrous, non reciprocating forward charging handle. The monolithic style has been achieved with a proprietaryinterlock between the upper and handguard. The slim-line handguard is M-LOK compatible for your favorite accessories.The Foxtrot Mike Products .45 Upper Receiver comes fully assembled and ready to drop on any pistol caliber lowerreceiver that uses Glock magazines. With its full-length Picatinny top rail and M-LOK compatible handguard, the FoxtrotMike .45 Upper offers plenty of mounting space for optics and other accessories.Features: Non-reciprocating fixed forward charging handle Left or right charging Machined from premium 6061-T6 aluminum. Proprietary handguard / upper interlock keeps handguard true to the upper M-LOK compatible handguard Limited lifetime warranty through Foxtrot Mike Products Complete upper includes bolt carrier group and charging handle. FM Muzzle Brake Compatible with Glock magazines