Feature:1. [Slotted Design] High standard slot design, can charge more than one battery, tighten the card position to avoid poor contact, more effective and convenient.2. [Safety Protection] The charger uses an intelligent chip to automatically control the voltage to prevent the battery from overcharging and to better extend the battery life.3. [USB Power Supply] USB charging design, can be used with a laptop, cell phone charging head, rechargeable battery, car charging, easy to use.4. [Easy to Operate] You can install the battery in the battery compartment, connect the power supply to start charging. Power level display, easy to check the charging status.5. [Premium Material] The use of high quality ABS, high temperature resistance, strong heat dissipation, to solve the problem of charging hot, more secure.Specification:Item Type: Battery BoxMaterial: ABSWeight: Approx. 195g/6.9ozSize: Approx. 9.7x6.6x5.2cm / 3.8x2.6x2.0in Applicable Batteries: 21700 Batteries (Not Included)Number of Rechargeable Batteries: 4 x 21700 Batteries (Not Included).Package List:1 xBattery Box(Battery Not Included)Note:Manual measurement please allow some errors.