The R90 Set - Hinged Ring Set for Stellarvue 80 mm to 90 mm Scopes by Stellarvue:

These 90 mm ID hinged rings have five 6 mm holes top and bottom. The holes are spaced at 60 mm and 1.5-inches apart and have one in the center. Works with tubes that are 90 mm in diameter which includes all Stellarvue 80 to 90 mm telescopes (except the #SV-SV90TF).

 OPT Product Number: SV-R90SET