I've seen these fittings. They look like a normal copper elboy or tee or whatever, but they have a ring of expanded area halfway across the mating surface. This groove is filled flush with solder, so that all you have to do is flux the pipe, stick this thing on, and heat it up.
I still think that the oven method should give better results when two flat surfaces are being mated instead of using some kind of groove.
Any word on how that seal came out? I like how easy and foolproof the oven technique looks. I'll have to try that once I get my hands on some copper.
