"I have recently used these blank-it protectors on a new build and have found them to work extremely well. These cardboard protectors fit well and withstand the process of plastering, leaving the enclosure clean and ready for second fix. I stripped the cables during first fix making second fix easier and no plaster was left on the cable or in the screw holes!"
"Great idea work fairly well, I would make one change to them and that would be to make the flaps longer so that the box sticks out from the wall a bit further, also you do need to strip the sheath on the cable first as the cable tends to push the box out, so the longer flaps would stop this! If you've ever had to find a socket box and chip away at it after an over zealous plasterer has been at it you'll love these."