"All of these push in fittings are so much better than the old junction boxes and block connectors. No mucking about with little screws in cramped loft spaces, just strip the wire back a bit and push it into the block. Even demountable with a bit of wiggling when you get it wrong. More than halves the time it takes to do a lighting circuit and cutting into a ring main can be done in under a minute. As they are clear plastic on top it is easy to check that the wire has been pushed all the way in. A bit more expensive than conventional joining but a massive time saving more than makes up for it.."