Squatmate - for better squatting.

light but sturdy – laser cut from aluminium tubing.
long battery life – enough for ~60 hours of continuous squatting!
the buzzer is loud enough to be heard over music. Unless it’s at mental volume. (But don’t wear a personal stereo, it’s not that loud!).
ambient light doesn’t affect the device.
want to squat lower or higher? Simple – just remove the top sections and either lay them on another object (e.g. a plate). Or for higher, tape them to bars on a power rack.
wide power rack? Don’t worry, the range of the device is several metres.

You simply set the pins for the squat depth that you require. Place the units at a safe distance apart (to eliminate the risk of tripping over). Align the units. Switch on the units and perform a test squat (without weight) to ensure the buzzer sounds and that the units are positioned correctly/safely for where your feet are normally placed. If everythings o.k. then happy squatting!

Note - this applies mostly to free squatting, not using a machine (as shown above).