KEEP PROTENTIAL DANGER AWAY - Powered with small button battery, this LED Slap band provides ultra-high visibility in dusk and nighttime activities. Keep you safe at night when do outdoor activitis, such as running, jogging, cycling & hiking. UPGRADED RECHARGEABLE DESIGN - Except the ensure the led armband works well, lanpard running reflectors improve the battery in rechargeable design. 2 hours charging, 3-5 hours working. Practicable, User-friendly and save money. LIGHTWEIGHT & EASY WEAR - Only 25g. The armband is lightweight to be used for wearer of all ages. Velco design for easy use. It would not give you any burden even in long time wear. Happy wearing, feel nothing. ADJUSTABLE - The Slap band has a adjustable size from 11"-13", by simply slap wrap it will fit on both adult and children for the wrist, ankle, and arm. To apply on the biceps, please consider the dimension to see if it fits on. PARAMETER - Color: Blue; Weight:25g; Package: 2 Pack; Full charging time: About 1-2 hours; Each time using: 2-5 hours; Size fit: 11"-13". Warranty: 180 days no reason refund