I have used butt connectors, solder connections and shrink tubing, but I was at Home Depot the other day and found these, that are a butt connector, shrink tubing and solder connection all in one.  The red rings contract when heated to clamp around the wire insulation and the solder melts to form a really nice splice.  They come in various sizes.  The instructions say to use a heat gun, but I found a butane lighter works just fine. Am I just behind the times or are these new?

I've seen them there too. We use yellow, blue, or pink/salmon colored butt connectors with a dialectric goo inside, they also shrink. Not cheap either, but they work well.

They're an outgrowth of the commercial industry. They've been around awhile, used for in-ground splicing in handholes, for sprinkler system solenoids, etc. Nice to know they're available retail!

First I used them was maybe a year ago in the shop.

Used them on my sprinklers a couple of years ago, really worked well, expensive as hell though.

The ones at Home Depot are reasonable I thought. I had a real tricky splice so I used one with shrink tubing over it. Mother nature will never get to that one!

I've used the ones with the shrink tubing but never seen them with solder. I always fill ALL electrical connectors with dialectric grease before crimping. Seems like the tubing would over heat and split by the time the solder melted ??