35 years of solder and wiring knowledge and unable to get a single solder butt connector to work from this kit. Even with my programmable top end heat gun, every temp setting from 450F - 850F would ALWAYS melt the plastic before the solder flows.The crimp connectors in the kit are fantastic. The supposed self-soldering ones are absolute FAIL with $250 heat gun, $25 Top Flite shrink gun and a variety of other torches and hours of wasted time. not a single solder connector worked for me. All they did is PLASTIC MELT!Bring a torch near them like in the photos for these, the plastic shrink will melt long before a drop of solder would ever flow. Even when JUST ABOVE solder melt temp (450-500F) the PLASTIC STILL MELTS OFF.