Review on 🔊 Adjustable Swivel Tilt Speaker Wall Ceiling Mount Stand - Black Bracket with Retractable Telescopic Arm - Ideal for Home Surround Sound System Bookshelf Satellite Speakers - Pyle PSTNDC31 (Pair) by Ashton Dahmer

Robust, flexible solution for mounting ceiling speakers. I would suggest providing an online installation template so you can determine the hole sizes and locations so a person can easily determine if it suits them. Second, change the mounting holes on the flat board. For example, the middle set of holes measures 4 1/8 inches on center. If you change them to 100mm, you can easily install speakers like KEF Q50A, which have keyhole mounting slots spaced 0.100mm apart. 100mm is a common measurement in home audio/video equipment. I did some work with the files and used them for exactly that. Good reliable gear.