These mounting rings fit refractors such as the Astro-Tech AT80, TMB92L, and all William Optics 80mm telescopes (Megrez 80 and ZenithStar 80, for example), plus any other scope with a 90mm OD tube . . .
These mounting rings fit refractors such as the Astro-Tech AT90EDT, current AT111EDT, Takahashi TSA-102, William Optics FL-105, plus any other scope with a 114mm OD tube . . .
These 142mm split mounting rings are designed to fit the Astro-Tech AT130 and TMB TMB-130 refractors, as well as any other refractor having a 142mm OD tube . . .