I use two layers of flannel - coordinating colors/patterns. I make them rectangle. I think this shape gives better coverage on shoulder and upper arm. They are also a good shape to put on your lap when holding baby on his/hers stomach. My daughters and nieces used them under baby's head in case spit up dribbled down while baby was on his/her back. Saved many a sheet! No more babies in the family but I make them for charity.