Our super smooth, hidden zipper is quick and easy, even on the wriggliest babies, because we know you don't have time to wrestle with snaps. * The feet on our sleepers are lined inside with the softest fleece for superior comfort, while the non-slip design on the bottom helps your baby gain traction and adds durability. We believe kids should feel free to crawl, climb, jump and explore. That's why we chose the softest, stretchiest bamboo fabric for our footed sleepers. The added stretch also means Peregrine sleepers fit twice as long as similar cotton styles, which is good because they'll quickly become your baby's favorite. The 95% bamboo 5% spandex blend is warmer and more breathable than cotton, so it's perfect in any weather. Harvested from sustainable bamboo, Peregrine Kidswear is as good for the earth as it is for your child's skin.