I purchased it from slingsandmore.com. It's a double sling made especially for carrying two babies. I would put it on so it crossed in front of me with the ring in the back. Each baby had a hammock sort of, in the front.
This worked when they were teeny-tiny, but not so much now. However, I think it's going to work great again once they both have good neck control and I can hip-carry them. I also use it for carrying one around.
It's my first time using a sling, so I don't knwo if it's the best, but I do know that I like mine.