The CuteBone Skull Dog Pajamas are made of 100% soft, durable and lightweight polyester minky to provide a comfy layer of warmth for those chilly days and nights. The 4-legs design with elastic waist and stretch that goes around the body not the length which is very friendly for dogs who have tails. And no need to worry about midnight potty breaks as most of our dog pajamas have an open belly for easy potty time.