The Geissele Super Modular Rails offer an ergonomic, modular and rigid handguard to suit a variety needs and missions. Each rail completely free floats the barrel and is machined from billet, aircraft grade aluminum. Rails interface with the receiver via a large barrel nut, to maximum surface area contact with the receiver. SMRs can be easily slid off the barrel nut, for cleaning and gas system maintenance. Each SMR includes a barrel nut and wrench for installation. MK2 features flat surfaces on sides and bottom. This SMR features a steall alloy barrel nut, for improved rigidity & strength. The MK2 also has a QD mount at the rear. Includes accessory rails. MK3 features flat surfaces on sides and bottom. The MK3 includes an aluminum barrel nut, for added weight savings. Includes accessory rails. MK4 features M1913 Picatinny rails towards teh muzzle, to alloy for quick and rigid mounting of accessories. The MK4 includes an aluminum barrel nut. The MK4 does not include accessory rails. MK1 features rounded sides and accessory rails attach directly to the handguard sides
SPECS: Fits AR15/M16 upper receivers. Aluminum construction. Matte black anodized finish. MK2 includes accessory rails. Steel barrel nut. MK3 includes accessory rails. Aluminum barrel nut. MK4 includes aluminum barrel nut. No accessory rails, as Picatinny rails are built in.