These 90 mm, felt-lined mounting rings are made out of solid aluminum, anodized, and will fit most 90 mm OD tubes, and all William Optics 80 and 90mm telescopes (Megrez 80 & 90 all versions, ZenithStar 80) and clone 80mm telescopes.
A worthwhile investment if you want the best out of your mount.
# Supplied with five threaded holes (external imperial threading 1/4x20; internal M6 metric threading) for mounting on most dovetail plates and WO dovetail plate.
# Equally holed on top to fit additional accessories.
# Nice comfortable knobs with teflon paint protection on locking end.
# Felt-lined to protect even the most delicate telescope finish.