Griffin Precision Mounts (GPM) are machined in-house in Watertown WI from lightweight aircraft-grade 6061-T6 aluminum. GPM mounts incorporate a dowel pin alignment system allowing use of the Accessory Interface Suite (AIS) of products affording ambidextrous modular accessory support. The unique patented design splits the rings on two parallel but offset planes allowing accessories to be mounted on five AIS mounting surfaces: top left right and 45° left & right offsets affording unsurpassed ambidextrous flexibility. Includes: 30mm Standard Griffin Precision Mount 12 (qty) 8-40 T15 fasteners for ring clamping 4 (qty) 10-32 fiber lock patched T15 fasteners for rail clamping 1 (qty) T15 Allen Key Shim Set (For setting the proper gap while mounting your optic) GPM Manual