A Moby is 18 feet by 2 feet of a stretchy cotton jersey. I'm thin, and it's not too much length at all, there's nothing to tuck in once it's tied. Having it as long as it is allows me to tie it in front where I can keep an eye on it, rather than in back where it hurts to sit back on. The super stretch is perfect for a newborn, but when they get bigger a sturdier fabric is often better, so my plan for summer is to go to the fabric store, pick a nice lightweight cotton without stretch and buy 21 feet (longer than moby for bigger baby and less stretch), and taper and hem the last foot on each end.
To learn how to tie it, read over moby's website some, and look up moby on youtube. It's super easy and I'm in love with my moby.
