This version of the Spuhr ISMS scope mount attaches directly to the scope rails on Accuracy International rifle chassis systems - no need for drilling, tapping, or separate rings-and-base. The Ideal Scope Mount System is a revolutionary scope mount with multiple attachment points for accessories like red dot sights, angle / cosine indicators, and other add-ons needed by precision rifle shooters. The built-in level helps prevent you from canting the rifle and compromising accuracy. The entire ISMS is machined from a single piece of aluminum billet, ensuring it will not flex under heavy recoil. This sturdiness protects the scope from slipping out of alignment under recoil or, worse, be Mfg: Spuhr