even wire attached, so you can have a third wire out... There is also one style that works quite well for terminating coax cable... solders the braid, gives you a wire out and then shrinks and seals the core.

The only real hassle is using them in a tight location... you need room for a heat gun. I find heat guns with those curved heat shields work best.

The other problem is that these are pretty much permanent. You pretty much have to cut them out/off to get to the wires inside.

Some of the suggested methods did offer a way to get to the connection once again after removing the outer protective cover. The method outlined below offers a way to get to a connection later:

Another thing we used in the military was rubber tape and rubber paint. I can't recall the names of the products, but it seems they were 3M... "Scotchkote" comes to mind. We would typically make some connection that was in weather, (for an antenna or a control unit) then cover it with this rubber self sealing tape, then paint it with Scotchkote. We could come back to that connection years later and simply slice the "boot" that we had made to find a perfectly clean connection inside.... and I am talking RF connectors with silver plated shells... stuff that a salt water environment would just eat up... was fully protected by this system.

The rubber tape was self vulcanizing... or self fusing. It came with a thin layer of clear pull away plastic liner attached to one side of the tape... and when you wrapped the tape around something it would seal to itself. That was then painted with the Scotchkote.