Sky-Watcher 0.85x Focal Reducer/Corrector for ED80 S20200 B&H
Starizona SCT Corrector LF - Large Format Reducer/Coma Corrector
Amazon.com : Astromania 0.5X Reducer for Photography and Observing - 1.25" Filter Thread (28.5x0.75MM) on Both Sides - Reduces The Focal Length for Visual and Photographic Use : Electronics
Vixen Telescope Focal Reducer HD — Explore Scientific
Reducer - Corrector | Celestron
What can a field flattener or focal reducer do for my telescope? | BBC Sky at Night Magazine