*** Helpful Tips *** Our Back-Zip Onesie is designed to offer a snug embrace. Its stretchy fabric accommodates wear over clothing or pajamas without necessitating a larger size. Should it feel too loose, consider opting for a size down for a snugger fit. The back zipper opens fully, catering to unique needs. We recommend partially zipping up (approximately 10%) before dressing your child to facilitate effortless dressing.