90pcs Solder Seal Heat Shrink Butt Connectors Waterproof Marine Automotive Electrical Butt Terminals Wire Connector Set (4 Colors/4 Sizes)

These shrink just fine, and the sealant on the end is good, but the solder doesn't want to melt until the jacket is scorching. The smallest ones probably work fine, the 16 gauge (red) is just enough to melt. The yellow (12 gauge) I could not get to melt onto the wire even while the jacket was scorching and burning. I would not buy these again.

These little buggers are great. I screwed up the first one, note: don't crimp the solder part. It all shrinks down real nice, the solder part takes longer and more heat than you might expect but eventually you'll see it bond to your wires.

I didn't like these as much as I'd hoped I would. When you get them hot enough to melt the solder, you also over-soften everything else and, in my opinion, it makes for a less than attractive wiring job. I think I'll stick to just solder and heatshrink the 'old fashioned' way.

I love this! Best connectors you can find. Good price and a great kit. Very easy to use. Fast delivery as well.

This product has shrink tubinh in clear so you can see the bond. A hot air or catalitic heat source is advised. I tried both and a lighter. All worked good. You have to be cautious not to burn yhe tubing. The solder joint on the wires worked well. I foend it better to strip long and wiggle them in so they overlap each other. Nice clean joint.

They make very good connections. The only negative, is that sometimes it takes a lot of heat to get the solder to melt. But overall a good product.

After 4 minutes of low and high heat gun, everything shrunk except the low heat solder. I then went another minute on high, and the solder never attempted to melt. This product isn't worth the box it came in.

Total fail, I wouldn’t trust them on any serious connections. I tried a couple of the yellow size to splice 14ga THHN stranded, the insulator just melted, the solder never did melt or try to bond the wires. I opted for real crimp connectors with heat shrink insulation.