4 Accessory 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, Roundness and Cylindricity with tolerances as low as 0.0002"; 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