Sliding cover to selectively "disable" a ThirdReality motion sensor by blocking the IR port.

Used to control the brightness of task lighting in a shared work area.
When doing fine work with little movement this is used with the cover down, placed close to the work area with the sensor programmed to set the brightness to max. 
When finished working the sensor is flipped over and the cover slid down (to the top?) to disable the sensor, stabilize it in an inverted standing position and return the lighting to normal.