Mounting the RE110P motion sensor

Quick question - how do you mount RE110P motion sensors? I see the side mounting options on the case bottom, but how/where do we drill for rear mounting? I see the 2 keyhole notches, but they look upside down to me - if I cut them out, then the sensor would have to slide UP to be locked in place - which seems counterintuitive. Also, I’m guessing that the flat heads are for side mounting only - I’d have to buy new screws for rear mounting?

This post addresses your question.

Without the gimbal you can mount the RE210P in a corner at 45 degrees by drilling/screwing through the angled corners on the back of the cover. If you want to mount it at another angle or tilt it up/down then you need the gimbal but the most common corner mounts is just a straight 45 degree angle. Carefully pop the circuit board out of the back cover before you drill to avoid accidentally damaging it. You can pop it back in after the back cover is mounted.