USB is rechargeable and easy to use: no longer repurchase and replace the battery for your luminous Doudou, just use the standard USB port of your computer or mobile phone charger. Press the button in the middle of the LED light to turn it on/off. Different brightness: three kinds of brightness are available, strong light (illuminating for 10 hours), medium light (illuminating for 15 hours), low light (illuminating for 20 hours) Convenient to load and wash: just pull the edge of the sock cap and push the lamp inward to separate them and wash the cap or charge the lamp. The 4 LED lamps have a high-quality IP44 waterproof rating. Elasticity and universal size: This winter warm LED knitted hat can fit most children, men and women of various head sizes, with high elasticity. Suitable: It is the perfect flashlight for camping, partying, cycling, barbecue, car repair, fishing, jogging or walking with dogs on cold winter nights.