The Spuhr ISMS is simply the best scope mounting system that money can buy. If you're looking for the best, look no further. Pairs of rings are obsolete.
The ISMS is a true system, that you can configure with accessory parts and mounts to exactly fulfill whatever your individual needs are. The quality is extraordinary, and once you see one, you'll understand why they're the best.
This particular model has a longer spacing between the rings, to accommodate scopes with larger turret assemblies. It beautifully fits my US Optics 5-25x58, which has a very long turret section. It is the perfect fit for this scope on a Remington 700 type rifle.
It has a 6MIL/20.6MOA tilt built in, for mounting rails that do NOT already incorporate a tilt. (If your rail does, then you need on of the 0 cant models.)
I have never used a scope mount that has impressed me like this one does. Try one, and you'll understand why. It is a gigantic leap beyond traditional scope rings, or any of the other one piece units I've seen. Particularly with precision rifles, there are things you absolutely can't skimp on. The scope is one, and how you attach that scope to your rifle is equally important. It must be perfect to extract the maximum benefits of your weapon system. Try a Spuhr and you'll never regret it.