It's mounting point has marks from use.
Details from the web:
The WITTY ONE enables extremely fine movement adjustments in both directions and has a standard sized dovetail for all Vixen/Celestron/Skywatcher/Bresser/ viewfinder mounts to use WITTY ONE on your OTA.
Just remove the stock viewfinder and put the WITTY ONE Tangent in its place - and fix on top of that, a large view finder/normal finder or a camera and they can then be adjusted and pointed using very fine adjustments for pin point accuracy.
WITTY ONE can cope well with accessories up to 1.5 kg.
In addition, the WITTY ONE has the Standard photo-threaded hole in the base plate, and thus fits every photo tripod with this standard threading.