Ultradyne UD Picatinny Chassis Spigot Armor Black. 4 inches of perfectly aligned Arca rail capacity. The M-LOK slots also make it possible to attach additional accessories including Picatinny rails. It is machined from 6061 T6 aluminum and is easily installed with three screws. Specifications for Ultradyne UD Picatinny Chassis Spigot: Manufacturer: Ultradyne Length: 4.4 in Weight: 2.4 oz Finish: Cerakote Fabric/Material: 6061-T6 Aluminum Features of Ultradyne UD Picatinny Chassis Spigot MLOK hardware included Textured for comfort Package Contents: Ultradyne UD Picatinny Chassis Spigot Installation Hardware Included Ultradyne UD20177-AB: UD Picatinny Chassis Spigot Armor Black