Bamboo Sleep Sack | Midnight BlackBreathable bamboo fabric in a black and tan checkerboard print Temperature regulating and ultra stretchy viscose bamboo blend Available length 0 6 Month: 27" Available length 6 18 Month: 37" Available length 18 36 Month: 40" TOG measures warmth and heat retention Use higher TOG for cooler months and lower TOG for warmer months TOG 0. 5 Shell: 95% Viscose Bamboo, 5% Spandex TOG 0. 5 Lining: 95% Viscose Bamboo, 5% Spandex TOG 1. 0 Shell: 95% Viscose