I've used both the Shark Bights and the Gator bight or Gator grip, can't remember the right name for that one. One is from Lowes and the other from Home Depot.
You do have to support them and I had the hardest time believing they would actually seal. But they do, and work great. All you do is take 2 ends of copper you want to join, clean the burs off, and slide them together. If you remember those Chinese handcuffs we all had as kids? Your fingers went in really easy but the harder you pulled to get them apart the more it bit into your fingers. Just slide the piece on 1 of the ends and then put the piece over the other pipe. Pull the pipes towards each other and your done. It takes a special tool to get them back apart. The tools come in a pack of 3 for about 2 dollars so you know it isn't much. It's a plastic piece cut to fit in the slot on the Shark Bight and you just pull it towards the pipe and it opens back up. Don't know if you can reuse it after taking it back apart. I was a chicken once it came back apart and just put on a new one. I can tell you it takes no special skills and compared to running a torch inside a wall, there is a lot less to worry about too. Both stores have them in the plumbing area and I'm not remembering the price right now. Seems to me it was between 3 and 4 dollars. Well worth it if you aren't comfortable soldering. [Non-text portions of this message have been removed]
