One piece IMS mount for 30mm Rifle Scopes. Extremely durable lightweight aircraft aluminum. Perfect height and eye relief for AR Flattop rifles. 4 screws for each ring top that seat into steel inserts. This model has a 20MOA cant built into the mount for long range shooting. A perfect mount for a .308 AR. Leupold Mark 4 IMS 30mm 20-MOA Scope Mount 171987