I have 12 volt recessed lighting in basement; dozens of corroded ceramic sockets. Changing the bulbs and cleaning were no help (MR16's with straight pins). I bought replacement sockets and because of the low voltage and dampness, I was planning to solder all these, on a ladder, with very short pigtails in the ceiling fixture (can). I bought these connectors as I wanted solder and heat shrink. My first connection I tried a flame (butane) but that was too much heat. I switched to hot air gun, and after 10 secs or so I could see the solder melt and run, then removed heat. I did 6 fixtures in an hour and a half, these connectors saved me ! All tested fine after first attempt, so they are a little forgiving as the first two I butchered but they worked fine. After 5 or 6 butt splices, I became very proficient. I plan to buy some more of these! All wires were 18 AWG so I have no comment on the very small ones or the bigger sizes. yet.