Quality materials :The baby milk warm bag made from high quality Oxford cloth, our bottle insulator is strong, durable and waterproof, with an insulating layer in the middle for faster bottle heating, which is ideal whether you're out at night or on the go. Universal size :The insulated bottle bag inner diameter of insulation sleeve: 55mm-75mm/2.2-3inch,suitable for a variety of milk bottles,can store milk cups,drink cups or coffee cups,which is very suitable for walking,shopping and traveling. Three adjustable gears :3 levels of adjustable, temperature adjustable,The portable milk warmers primarily warm cold milk or water and keep a constant temperature for 24 hours, preventing it from getting cold. Portable bottle cover :The bottle heating cover come with USB cable, just connect the cable into any power bank, mobile phone charging lines ,vehicle or laptop interface,plug-in can be heated at will . Suitable for all occasions :The portable milk warmers can adjust the required level according to the seasonal temperature, the highest level is about 60 , the middle level is about 50 , the low level is about 40 .Perfect for cold winter days at home, going out, travelling, shopping, walking etc.