I saw one at YCN. It's hard to explain it. I suppose the best way is: it's like two rolled up towels and the rolled up towels are attached with a piece of flat cloth in the middle. So, the baby lays on the flat piece and on either side has a rolled up towel. That's prolly not a good explanation.

I was in a baby store on the weekend and safe'n'sound make one too. I just cannot find picture of one on the 'net to give you link for.