I’ve seen those before but have always been skeptical of how well the solder actually penetrates the conductor. Sure a heat gun will make the solder melt because it’s low temperature, but that doesn’t change the amount of time it takes to heat copper. It does look like a neat product if it really works. It just isn’t for me.
Yeah I dont think it penetrates more like squeezes. But sealed squeezed its not gonna fail and current is gonna flow without resistance and its sealed. But you gotta go with what you like and what works for you.