SwaddleDesigns zzZipMe Sack is perfect when baby is ready to graduate from swaddling. Made from the same breathable, preshrunk 100% cotton flannel as our Ultimate Receiving Blankets with soft satin trimmed edges. The zzZipMe Sack is a wearable blanket that features a clever 2-way zipper (patent pending design) - opens from the bottom as well as the top! The zipper zips down from the top making it easy to place baby into sack and also zips up from the bottom keeping baby snugly warm during diaper changes. So easy! This zzZipMe Sack has a TOG rating of 0.7 which is appropriate for temperatures of 72-78 degrees F caused by warmer weather (the temperature range medical experts recommend for sleep environments is 65 - 70 degrees F). Machine washable and proudly made in the USA.