Abstract: The disclosed invention is a rail cover for use on mounting rails typically, though not exclusively, use on personal firearms. The covers may be made to fit either Picatinny or Weaver type rails and feature a clipping structure on the cover's underside that grasps the rail while the tension in the cover body holds the cover in place. Two preferred embodiments disclose a solid cover and a low profile, ribbed cover that nests within transverse grooves in some rails. Alternatively, a restraining beam may be utilized to further restrain the clipping structure and retain the cover on the rail.