"I've used several of these in lofts and eaves cupboards to hold bulbs. They are small and easy to fit and a 0.5mm flex can easily fit through the knock out on the side of the holder.
If you want to have something simple in a loft or cupboard these are ideal. If you want something to replace a ceiling rose and which may need loop in wiring support then don't buy these - buy an MK or similar instead."
"I usually use crabtree but they were sold out, so I bought a couple of these. The instructions said to wire in with the live fixed and the neutral switched! A little digging round the net, I read that the instructions were changed at a later date, shocking! The terminals are fiddly, does not feel solid at all. Just buy something else."