During the first year, after baby has transitioned from swaddling, experts recommend a wearable blanket for sleep. The Muslin zzZipMe Sack features a handy 2-way zipper that makes our sleep sack easy to use. TOG 1.5. Easy to place baby in the sack when unzipped from the top and keeps baby warm during diaper changes when you zip up from the bottom. Award winning design features baby velvet fabric with silky satin trim.