GASCO R407A 1000 PPM Balance Air Calibration Gas 34 Liter Aluminum Cylinder C-10 Connection 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 Air CONDITIONING EQUIPMENT