GASCO EB-50-50 Carbon Monoxide 50 PPM in Air Calibration Gas contained in a ecobump aluminum cylinder, Material: Aluminum Alloy, Pressure: 1200 PSI, Dimensions: 4" x 2", Water Capacity: 0.066 Liters, Multiple Bumps: Approximately 250 bumps per cylinder, Free shipping No Haz-Mat, Certification NIST (ecobump regulator sold separately), Made in USA