Attention : The positive pole of the battery is connected to B+ and the negative pole is connected to B-, do not reverse it. If it is reversed, it burn out overcharge protection, overdischarge protection, short circuit protection, constant current.Suggest Working Conditions:Max continuous charge/discharge current 1.5/2.4A,working temperature: -5~45℃. Specifications: Size: 6.5 x 2.5 x 0.1cm IR of PCM : ≤65 mΩ Allowed 0V change: Yes Constant current: 2.4A Dual output current: 5V 2.4A Input voltage B+ to B-: 3.0 - 4.2V Charging cable: support and Android three USB Cables Button function: and hold the button after standby, the LED digital screen displays the power Prevent Overcharge Protection: Detection voltage: 4.20±0.05V Release voltage: 4.100±0.05V Detection delay time: Less than 200 ms Prevent Overdischarge Protection: Detection voltage: 3.0±0.10V Release voltage: 3.10±0.10V Detection delay time: Less than 100 ms Short Circuit Protection: Short detection delay time: Less than 50 uS Release Conditions: Cut off load Color: As Shown Material: PCB Package Contents: 4 x 18650 Charging Board 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.