The holder was used in converting kitchen lights from MR16 to GU10 bulbs. The connecting device was of no use in my application as was able to connect the holder cable into the mains junction box that was accessible.
Haven't fitted yet, but looks like a nice little unit
These are super easy to use.. which is good, i'm no electrician. But honestly, I also got the kind that don't have the fastfix connection - and they're basically just as easy except you have to use a screwdriver with the other ones, and you don't with this one. But yup.. a wee bit more expensive, but easy peasy