Switching Frequency up to 1MHz Quasi-CV mode to Compensate for the Voltage Loss on Battery Internal Resistance and Trace Resistance Automatic Recharge Protection for Battery Voltage Being Low than Input and Short Battery Good adaptability to Input Supply with Limited Driving Capability Battery Overvoltage Protection Led indicator: "" LED is charge status indicator "OK" LED is fully OR Constant voltage mode; Widely used High safety performance Simple and easy to understand and operate Battery overvoltage protection Operating Ambient Temperature-40Celsius to +85Celsius Size 39mm x 18mm x 6.3mm Weight: 5g/pcs Parameter: 2-Cell(2S) 8.4V Version: Input voltage: DC 3-6V(Recommend DC 3.7V 5V) Input current: 1A(1A Version); Charging voltage: 8.4V Charging current: 0.55A(1A Version); Colour:black Material:PC+Metal Package Contents: 4 x Li-Ion Charger Module Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.