The Spuhr interface for my Sniper Tools Inc. Angle Cosine Indicator is excellent. You have varied options where on your Spuhr mount you would like to mount it based on your preference. It ACI is held securely and if you move the mount over to another rifle you do not have to remove it. The ACI makes it easy to quickly correct your DOPE for shot angle. If you shoot or hunt in rugged terrain I recommend both the Spuhr mount and ACI interface.