This is a new or at least new to me technology.
These connectors look like a standard crimp connector. They have a solder pellet/ring molded into the shrink tubing that you pass the wire/wires through then heat.
The solder melts making the connection and the shrink tubing seals all in one step. Directions call for a electric heat gun but say a torch will work but guard against scorching.
Online demo shows a connector holding an 8lb weight and not coming apart.
Sure looks easier than the traditional soldering process especially in tight spots.