KRISS USA, Inc Receiver Extension Kit, Picatinny Side Rail Kit And Mounting Hardware, Fits GEN II CRB, Flat Dark Earth KVA-VMRFD01 KRISS USA's Vector MK1 Modular Rail is designed as a bolt-on handguard extension for your KRISS Vector CRB" and is made from aluminum alloy and coated with a Cerakote ceramic firearms coating. The rail's shape follows the form factor of the KRISS Vector's body and is milled to reduce weight while still maintaining a rigid structure for support. The KRISS Vector MK1 Modular Rail features female threading along the three o'clock" six o'clock" and nine o'clock surfaces for the attachment of the included KRISS Vector Picatinny Side Rail Kit which comes pre-installed on the handguard. The MK1 Modular Rail mounts directly to the body of your KRISS Vector and is compatible with Gen 2 models only. It will not fit the Gen 1 Vector due to its integrated flashlight mount.