OP
Corpy76
basically, a plastic spacer that goes between the socket and the wall, allowing plasterers and tilers to work up to it without exposing live terminals. removed after work is finished. generally use them when the sockets are required to be used and 2nd fix is done before plastering etc. google it.
I had a look at these they look good but why do things twice? You still have to go back, remove the yoozy box and recheck your connections. Then surely you have to do a full initial test and inspection (which should have already been done prior to energisation with the yoozy boxes fitted), to check for things like the good old nicked cable with the socket screws etc.