This 40-slot Picatinny rail measures 404.8mm (15.54") in length and 9.5mm (0.374") in height and is machined to MIL-STD-1913 and STANAG 4964 dimensions, providing a secure mount for optics and various other accessories. We offer rails in either of two profiles; flat base or a 8.5mm radius base that is specifically designed for the HK91, G3, Cetme C, ect. Machined out of 1018 steel these rails are readily welded and do not require any pre or post weld heat treatment. They can also be attached by drilling and tapping for screws, and/or epoxy. All rails have a uniform media blasted finish and are shipped lightly oiled for corrosion protection.