The fabric is very light.It’s only about 0.5lb.It provides a cozy and breathable feeling for your child. Straddling Legs and widening hip. The baby can play leisurely and carefree before sleeping whether sit or run .When they feel tired they can easy to sleep and don’t need to change other sacks.THE MOST IMPORTANT is the bag will not twine when baby turn over Long zipper extended to hip. It??s convenient to change diapers when baby fall asleep revent even a minor bump. Zipper cover at the top and the inside to prevent rubbing the delicate skin of your baby. Two layers in front to keep warm like covering a blanket.One thin layer in back for perspiration and breathability because baby is easy to sweat.