The inner diameter of the tube rings is 70 mm for Telescopes between 43 to 70mm tube diameter can be mounted adjustableThe adjustment Nylon-tipped thumbscrews for avoiding unaesthetic scratches and pressure marks on the telescope while still ensuring reliable clamping.Solid metal guide scope rings for Finderscope or Guidescope with knurled metal screws12mm diameter of Big screws with maximum grip allow easy use - even with glovesThe mounting bar has two M6 through-holes on both sides for easy adaption to rings.Three threaded through-holes: the center hole has UNC 1/4-20 and the two larger holes on either side of center have M8x1.25Colour:blackMaterial:Aluminum alloySize:Length 89mm; ring diameter 70mmPackage Contents:1* Guiding Scope Ring KitOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.