* 1.2 inch super high brightness LED display, 5 digits. * ∑－Δ ADC with super strong EMC characteristic and stability, devision selectable. * 6V4Ah rechargeable battery inside with charging and low voltage protect circuit. * Low power consumption, the battery can be used for 60 ~ 80 hours after recharging. * Keyboard calibration with hardware lock. * Easy to operate，option for wireless remote controller