The Gro-suit has been specially designed to be used with a Grobag Baby Sleep Bag in colder temperatures. The quilted sleeves will keep your baby's arms warm, with no neeed for additional bedding or layers. Quilted sleeves for cosy arms Single layer on areas that are underneath the Grobag so your baby won't overheat Popper for easy changes Comfortable stretchy collar Twin pack 100% super-soft jersey cotton Quick-dry polyester filling on arms Can be used with any baby sleep bag without arms