Spuhr Picatinny-style rings are not just rings; they are 7075 T651, machined aluminum ring systems. Each set of rings are equipped with 7-8 interface mounting holes that allow attachment of many common secondary sights and accessories. The rear ring features a built in level that requires minimal movement from your shooting position to view. Spuhr ring sets feature all the same attributes of the ISMS Unitmounts and provide an alternatively lower mounting solution.