Product Input voltage: 5V Charge cut-off voltage: 4.2 V 1% Maximum charging current: 1A Over-discharge protection voltage: 2.5V Overcurrent protection current: 3A Size: 26 x 17 mm Battery holder Type: 3.7V Material: durable plastic Size: 75 x 20 x 13 mm Product List: 3 x boost converters 3 x charging module 5 x battery holder 1. Boost Converter: With this mini boost converter, you can easily create a power supply unit such as 9 V, 12 V, 15 V, 18 V, 24 V etc. with adjustable output yourself. Boost Converter: Used only to increase the voltage and not to decrease the voltage. 2. Steps for Boost Converter: Connect the power supply, turn the twist knob on the blue potentiometer 15 to 20 rounds counterclockwise and monitor the voltage with a multimeter to get the required voltage. 3. Battery holder: The battery holder is intended for a 3.7 V 18650 lithium-ion battery. 4. Wide range of applications: DIY mobile power supply, power supply monitoring, camera power supply, vehicle power supply, communication equipment power supply, etc. 5. Compatible Each level shifter can convert 4 pins on the high side to 4 pins on the low side, with two inputs and two outputs for each side. Power input with anti-reverse connection protection, built-in 3.3VLDO and can supply an external current of no more than 150 mA. Compatible with breadboard, can be used in breadboard directly