Bamboo Sleep Sack | GreyCozy and eco friendly sleep solution Breathable bamboo fabric for comfortable, safe nights Temperature regulating and ultra stretchy viscose bamboo blend Lengths by age: 06 months 27"; 618 months 37"; 1836 months 40" TOG measures warmth and how quickly fabric uses heat Choose heavier TOG for cooler months and lighter TOG for warmer months TOG 0. 5 composition: Shell 95% viscose bamboo, 5% spandex; Lining 95% viscose bamboo, 5% spandex TOG 1. 0