Losmandy Guide Scope Rings (Losmandy PN DR 90) 90mm (3.5") I.D. rings with three point adjustment, Delrin tips. Wt. 1.25 lbs. per set, 2 rings per set, dovetail mounted, no tools needed. I.D. size from 1.7" TO 3.5", Ht. from top of dovetail plate to center of rings 3.25", (I used these for a Sky 90), $110 includes shipping anywhere continental US.