High quality made 90mm tube rings by Rother Valley Optics. These are finished to a very high standard. The feature a clamp design with large silver locking knobs for ease of use. They are threaded in 3 places on the underside and on the top
These 90 mm, felt-lined mounting rings are made out of solid aluminum, anodized in black or silver, and will fit most 90 mm OD tubes, and all William Optics 80 and 90mm telescopes (Megrez 80 and 90, ZenithStar 80, GT81).