Framework structure with pressure limit-protectionoverloaded and low voltage indicationac-dc dual-use, built-in rechargeable batterylong lasting power can be used up to 120 hoursautomatic standby mode if no operation in 10 secondsfour configuration memory unitsautomatic temperature compensationexternal dc power: working voltage: 6v ±10%working current: 500maexternal ac charging voltage: 110 to 220v