The UIT rail, also known as Anschutz rail, is a standard used for mounting slings and other gun accessories in competition shooting, and is essentially a T-slot track shaped aluminium extrusion profile accepting attachments in the form of T-slot nuts, or similar.[1]
A similar design is called Freeland rail, but the dimensions of Anschütz (UIT) and Freeland rails differ.[2] The Anschütz rail is wide and shallow,[3] and the Freeland is narrower and deeper. Accessories made for one of the two types are not necessarily compatible with the other.