MDT Premier 30mm High Scope Rings - Black - MDT's Premier Scope Rings offer a solid, light weight mounting system for your optics. Made from precision-machined aluminum. MDT Premier Scope Rings are designed and manufactured to STANAG 4694 specification, also known as "NATO spec". This means the scope ring sits tight to the top of the scope base rail, with pressure being applied to the underside of the angled rail surfaces to maintain a solid interface (as shown below). This design also allows mounting on out-of-spec rails: