This is a Seekins Precision Mount known as the 20 MOA, model 0010640010.
MXM = Monolithic Extended Mount The best rifle in the world is useless without the perfect mounting system. Seekins Precision's MXM Scope mounts are precisely machined from billet 7075-T6 aluminum to rigidly mount any optics to your rifle. Seekins Scope Rings never need to be lapped or altered in any way. Scope Rings are .8" wide to provide more clamping surface area than any other ring on the market. All rings are Type III Hardcoat Anodized matte black for a durable non-glare finish. Built to the 1913 Picatinny specification" Seekins Precision Scope Rings have a center lug machined directly into the bottom. This integral" flat recoil lug is far superior to cross bolt lug designs and fits precisely into Picatinny slots with minimal clearance. For maximum torque and strength" Grade 8 T-25 Torx(R) fasteners are used that will not strip out while being tightened to the appropriate specification.
Features:
Grade 8 T-25 Torx fasteners
Center lug machined into place
CNC machined 7075-T6 Billet