Loulou Lollipop Short Romper Tiny EngineersSoft Warm Weather Comfort for Active Babies Cool, comfortable, and soft against sensitive skin the Loulou Lollipop Short Romper in Tiny Engineers is built for active babies in warm weather. Key Features Made from TENCEL Lyocell with spandex for soft stretch, based on the official product page. Official copy says the fabric helps manage body heat and moisture for warm weather comfort. Naturally hypoallergenic fabric with thermal regulating properties