This is a wall mount for a braun therm-scan. It is sping-loaded and enables you to take only the thermometer off the wall or take the whole mount oiff, without unscrewing anything.
Printed mine in PLA, and after a year or so, no problem with the spring.
To mount the thing on the wall, drill a hole for the small hole and in the center of the long hole. this gives enough room for the spring to work.
Put the holder with the bottom first in the mount and press it up until you can lever it flat on the wall. then when releasing the pressure, the upper catch also clamps the holder firm.
The author marked this model as their own original creation.