The Portagreen Calibration Gas Air 30 is a calibration gas used to calibrate and bump test gas detectors. It contains 30% oxygen balance nitrogen and comes in a 34 liter cylinder with CGA 590 outlet connection. The gas has a 2 year recommended shelf life and is available in high pressure cylinder sizes of 34L, 58L, 103L, and 116L. This calibration gas meets ISO 6141 standards and is suitable for calibrating and bump testing many brands of portable gas detectors.