This 40-slot Picatinny rail measures 15.54" (404.8mm) in length and 9.5mm (0.374") in height. We offer these rails in either of two profiles, flat base for universal or custom fit, or a .669" (17mm) diameter base for the G3 and Cetme C and variants. Machined out of 1018 steel these rails are readily welded, do not require any post weld heat treatment and are machined to MIL-STD-1913 and STANAG 4964 dimensions, providing a secure mount for optics and various other accessories. All rails have a uniform media blasted (white) finish are sealed in plastic and lightly oiled for corrosion protection.