Nightforce standard bases are a quality, affordable solution for those looking to ensure their scope is firmly mounted to their rifle. These aluminum bases are machined to Mil. Std. 1913 rail specifications and hard anodized. Notes:The 20 MOA base can be used to gain more usable elevation in your scope which can be a benefit for long range shooting. It is recommended that your scope has a minimum of 50 MOA max internal adjustment if it is intended to be zeroed at 100 yards. Mounting hardware included