These M-LOK compatible, 1913 Picatinny rails are designed for use with compatible stocks or handguards and provide for the attachment of various accessories such as bipods, lights, and grips. They are made from 6061 T-6 aluminum and come in a matte black anodized finish. Available in 4.5"11 slot and 2.5" 6 slot lengths. All attachment hardware is included. Color: Black Type: M-LOK Length: 2 1/2", 4 A 1/2" Slots: 6, 11 Weight: 1 oz, 2 oz Material: Aluminum Mfg: Xlr Industries