The scope base accessory for the popular receiver is offered in both black and silver with a low and high rise style. Our low scope base height is 5/16″ (about 1/4″) by 5 7/8″ long and incorporates the Picatinny spacing system similar to the military spec. We chose the picatinny spacing so if customers have more rifles than scopes they can use the same scope ring spacing on more than one rifle. It works just like the Weaver style bases and rings you are accustomed to, only the slot spacing is identical for every mount made, no matter what gun it is attached to. Both our low scope base and high scope base extend over the front of the receiver so our product doesn’t work with rear sights or if you need the receiver to fit into an outer shell such as the SR-22®. Scope Base and Scope Ring height recommendations: Rings for weaver and picatinny will work well with our mounts. For nearly, all 22 rifles, the low scope base and low rings work best. If you have a high mounting target stock or you prefer your head positioning unusually high then the high mount with low ring or low mount with medium height rings will work. We suggest low scope base and low rings with 40mm objective and smaller and a high mount with low height rings with 50mm objective. Package includes: scope base 4 mounting screws short arm hex wrench