AIM Sports US-AS003: Designed and built to fit most Mil-Spec AR15/M4 upper receivers. Boasting one of the easiest mounting systems to install in the industry, these M-LOK slim-line handguards provide superior fit, finish, and performance. This model is designed to work with low-profile gas blocks. This rail also provides seven rows of the mounting surface and has a streamlined 1913 Picatinny top rail. Type-III hard coat anodized.