Home - ZippyJamz Shop ZippyJamz baby sleepers, rompers, and onesies made of GOTS certified organic cotton, featuring an intuitive two-zipper design to make diaper changing easier. Available in sizes newborn to 3T. Shop ZippyJamz baby sleepers, rompers, and onesies made of GOTS certified organic cotton, featuring an intuitive two-zipper design to make diaper changing easier. Available in sizes newborn to 3T.