I designed these to go with my flexible build plate from Wham Bam Systems. They definitely fit the M2. I am not sure about the M3 and others. If you can verify the fit for other printers, let me know in the comments.
The front clips hold the bed in place to prevent it from lifting when you remove the build surface, but still allows you to remove the heater bed by lifting from the rear. You will have to remove the top rubber angle bracket and install this so it will be at the correct height for the magnetic bed.
The rear clips install on top of the rear rubber brackets and help align the steel plate as you drop it down on the magnetic bed. By leaving the rubber brackets on, the bed will stay stable and the fit will be more universal.
To drop down the build surface, just push the edge of the plate to the back and make sure it is centered between the clips and drop it down. It was not hard to drop the build plate on straight, but I wanted it to be super easy and I can do it sitting in front of the printer without having to look at it from above.
Just tighten these down until they just starts to make good contact. By gently tightening you will feel the point where it goes from almost no resistance to a bit more effort, stop there! Do not crush these down or you will have issues.
You will probably need to re-level your bed after installing these. The stock screws work fine.