I ordered these on a whim.. but, I have to say they are more than useful. They are QUICK,.. and you can throw 1, 2, 3, or more wires in these twisted, and crimp and not have to worry about them. They really speed up installation.
Pros: Can be used to simply crimp a single wire that isn't being used anymore to keep it from interfering.. to joining 2-3+ wires together in a nice strong crimp.
Cheap, and has a million uses in wiring!
Everyone needs a bag of these.
Cons: None.. I ordered on a whim, didn't think I'd really use them.. but I keep going to them due to ease of use and quality of the crimp.