The Blue Monkey's Tiny Tanks/Snuggly Undershirts are a MUST in every baby’s wardrobe. Their multi-purpose function makes them wearable 365 days of the year – wear alone in the hot summer months as a tiny tank to keep baby cool and under clothing in cooler temperatures to keep baby’s chest warm. They are perfect under school uniforms, for baby yoga, and on summer nights, with just a diaper or pyjama pants. Cotton/polyester mix (cotton for breathability, polyester for stretchability). Easy to care for – just throw in the washer and dryer!