Features FOR 18650 BATTERY: This tester is specially designed to measure the capacity of 18650 batteries. The 1.77 inch display screen can simultaneously display information such as internal resistance, capacity, voltage, current and level drums. MULTIPLE MODES: The detector measures single channel capacitance and internal resistance; Takes separate and discharge, with a maximum of 9 cycles and discharge in automatic mode. HIGH PRECISION: Using the 2-wire DC method to test the internal resistance of the battery, the digital precision is high when the battery is fully charged. DIY METHOD: Method 1: Install a 21700 battery holder; Method 2: Test by connecting an extension cord or alligator clip to an external battery. DATA RESET: When shutting down or changing modes, the capacity, energy and time data will be automatically reset. Specification: Item Type: Battery Internal Resistance Tester Material: PCB Battery: 2 x 18650 lithium batteries (not included) (power x 1, test x 1) Model: XH M239 Display accuracy: 0.1 Measuring accuracy: 1 mAH Standby current: 5 mA Discharge current: approximately 500 mA Power: 10 W 8Ω Applicable Batteries: Suitable for batteries meeting 2.5-3.5V shutdown discharge voltage, 2.8V start-up to 4.2V fully charged. Package List: 1 x Battery Internal Resistance Tester Package List 1 x Battery Internal Resistance Tester