Mini Ultrasonic Design Exquisite Design | Compact Size | Easy to Carry To achieve a perfect look and superior technology, the design team, after years of experience, used ultrasonic welding technology to create this product in one piece, resulting in a screw-free design. The fast charger is compatible with a variety of common rechargeable lithium batteries. Retractable Design Spring-loaded battery compartment supports 21700/26650/18650/16340... Charges multiple types of lithium batteries. Multi-function charger Compatible with a wide range of 3.7V-4.2V lithium batteries. Current Regulation and Fast Charging Trickle charging at 0.1A below 2.8V, constant current charging with OV protection activated, CC charging, and constant voltage CC charging to improve lithium battery efficiency. Product Specifications Smart USB Multi-function Lithium Battery Charger Dimensions: 105x25x29mm Weight: 27G Input: 5V2A or 5V1A Output: 0.8A Compatible with various models of 3.7V and 4.2V lithium batteries