They're great for Romex solid wire, but stranded wire is a total mess. I installed headlights, and headlights have stranded wire. I spent more time getting the wires in than they were worth. I've tried soldering stranded wire in place and even trying to insert it the wire broke where the wire jacket began. I ended up soldering single core wires to stranded wires. Just using wire nuts would take half the time. I wouldn't buy them again when dealing with strands.