M-501003 Honeywell equivalent by GASCO R123 Refrigerant Calibration Gas 500 PPM Balance Nitrogen R123 Refrigerant Calibration Gas in Nitrogen contained in a 103 Liter Steel Disposable Cylinder, For Use with Any and All Gas Detectors, Cylinder connection C-10, Calibration Certificate NIST, Made in the USA, Calibration Refrigerant Gas is intended for use in Calibrating Refrigerant Gas Detection Equipment Only. NOT INTENDED FOR CHARGING Nitrogen CONDITIONING EQUIPMENT