The MSA Four Gas Can is a mixture of gas that is used to calibrate the MSA Altair 4X and 5X multi gas detectors. It contains the appropriate amount of each gas to correctly calibrate the sensors. Having 58 litres of gas ensures there is enough gas for plenty of calibrations. The gas ratios are as following: 1.45% Methane (CH4) 60ppm Carbon Monoxide (CO) 20ppm Hydrogen Sulphide (H2S) 15% Oxygen (O2) Features and Benefits Premixed gas ensure long use time and accurate calibration of MSA Altiar 4X/5X gas monitors 58 litres of has ensures there is enough gas for plenty of calibrations