[MrForbes]

From the data sheet:

Operating angle: Tilt of 50 to 80 degrees, when the switch is tilted gradually (approx. 1 degree/s) from the horizontal

Returning angle Tilt: of more than 25 degrees, when the switch is tilted gradually (approx. 1 degree/s) from the horizontal

Just guessing....Looks like it is a switch, the contacts will open when you tilt it at least 50 degrees, but no more than 80 degrees, from horizontal. And they will close again by the time it gets back to having only 25 degrees tilt. This is what happens for slow tilting action, changing one degree per second.