this be absolutely not a fit for Optoma hd20 . I do not know how it fit other projector , but if you have hd20 look somewhere else . the mount assembly be too big for the tiny optoma and it be too hard to fit it in . if you try the centroid method the manual suggest , its nearly impossible to align the hole to match . once you put it together and mount it on the ceiling , it will still have some tiny wobble and adjust to fit the screen be quite a task . tighten the bolt do not really help so much . the only good thing be that the piece that attach to the ceiling be very strong and well build . in general , remember to loosen the bolt before hoist it on the ceiling . you will have to oil the bolt and put a lot of strength to loosen they . they be terribly tight . Stay away from it if you have a hd20 !