USB rechargeable No need to replace the battery, no need to charge frequently. It comes with 2 micro USBs so it can charge both the front and the back at the same time. There are 3 modes: slow flash, fast flash, steady Simple and comfortable Very easy to put on and take off, just slip it over your head and one arm. Since it folds up very small and compact, it is ideal for carrying around. protect yourself anytime, anywhere Weatherproof and lightweight We specially designed a small waterproof bag for the battery, you don't have to worry about damaging the battery even if you use it in the rain. Weighs only 80 grams, you can't feel it when you wear it Color: yellow Size: 80CM*5cm Quantity: 1 1. Due to different measurement methods, there will be an error of 1-3 cm in the product, please make sure there is no problem before placing an order. 2. Due to different monitors and light, the picture may not reflect the actual color of the item, thank you for your understanding. 3. Only the above package content, other products are not included.