Feature: 1. WEAR RESISTANT AND DURABLE: Battery charger module is made of premium PCB board, wear resistant and durable, good contact. 2. OVERVOLTAGE PROTECTION: Battery charger board has strong adaptability to input power and over voltage protection for battery. 3. HIGH PERFORMANCE: Boost lithium battery module preserves the battery voltage below the input voltage and battery short circuit. 4. INPUT VOLTAGE: Charging board input voltage DC 3-6V (DC 3.7V 5V recommended). Input current 1A (1A Version), 2A (2A Version), 4A (4A Version). 5. CHARGING VOLTAGE: Charger module charging voltage 8.4V, charging current 0.55A (1A Version), 1.1A (2A Version), 2.2A (4A Version). Specification: Item Type: Battery Charger Module Material: PCB 2 Cell(2S) 8.4V Version: Input Current: 1A (1A Version), 2A (2A Version), 4A (4A Version) Charging Current: 0.55A (1A Version), 1.1A (2A Version), 2.2A (4A Version). Package List: 2 x Battery Charger Module Note: Match the right model size before use