Oxygen monitor PM40 is designed for the low end of measuring the contest of oxygen in the welding area. By measuring down to 40ppm is a perfect simple solution to ensure a perfect weld. Technical specifications: Range Down to 40ppm Battery: up to 20 hours before recharging is needed Accuracy: +/- 5ppm Display: Digital Sensor: Thermo-electric Advantages: Battery powered No preheating time Weight: Instrument: 0,42 kg