Voted the No. 1 Wearable Blanket by The Bump in 2019, our bamboo sleep bag is buttery soft and keeps baby at a comfortable temperature all night long.  Exterior: 97% Bamboo Rayon, 3% Spandex Filling: 100% Polyester Highly breathable J-shaped double zipper 0.5 TOG: 23 - 26 °C / 74 - 78 °F TOG is a rating system that measures warmth and calculates how quickly a fabric uses heat. It is the standard when choosing the appropriate sleeping bag for your baby, depending on the ambient temperature in your nursery. We recommend a heavier TOG during cooler months and a lighter one during warmer months. Due to lack of quilting the 0.5 TOG Sleep Bag tends to run bigger and have more stretch. We recommend following our fit guide/rules found in the blog here to determine if it is the correct fit.