The BA Series Mounts are made for mounting high performance optics onto bolt action rifles with Picatinny rail scope bases. The mount is precision machined from 6061 T6 aluminum and finished in hard coat T3 Mil-Spec anodize. Horizontal split rings. The interface ensures positive engagement for both in spec and out of spec rail systems. Absolute Return to Zero via multiple locking lugs located on the bottom of the rail interface. Features: 4 Mounting Locations on the left and right side of the mount body, in the front and back. The holes are on 20mm hole spacing, which works with other Unimount accessories. Extreme bore size consistency within +/- .0002a ^2 Roundness and cylindricity of bore within .0002a ^2 Provides the ability to confidently move the optic/mount to multiple rifles with simple windage and elevation adjustments. Superior clamping surface to ensure maximum rail engagement. Lifetime warranty Length 4.760a ^2 Weight 6.8 oz Rail to optic center is the size specified on the drop down menu. This mounting system is designed to handle large objectives up to 56mm (34mm Mount) and 50mm (30mm Mount). MPA BA 1.125a ^2 Height - Erector Housing to main tube measurement of 0.210a ^2 or shorter