"These are a brilliant piece of kit. Switch off the mains, pull out the old type fuse holders, remove the cover over the fuse holder, replace with the new cover supplied (different colours for different ratings) then plug in the MCB. Switch on and job done! Just ensure that the correct rated MCB replaces each fuse.
No more fiddling about replacing fuse wire in the holder. The only drawback, if you can call it one, is that if a bulb blows the MCB MAY trip out, but we can live with that for the additional safety."