Interstate Pneumatics WRFCO2 accurately measures the flow of CO2, with this high-quality, rugged flow meter featuring self-centering flow tube and adjustable ball guide for easy use. WRFCO2 attaches to any CO2 cylinder with a CGA-320 valve fitting — Features: High quality CO2 regulator | Designed for grow rooms and green houses to enhance CO2 to the growing environment | Increases the plants metabolic rate; speeding up growth rates and yields by up to 40% | A must for optimum plant production in high light intensity gardens | Pressure Relief Safety Device, Solid Brass Body and Fittings | Manual valve | Self-centering flow tube keeps ball centered to assure flow accuracy (precise 0.5-15 cubic feet per hour settings) | Pressure gauge, brass alloy body, tank pressure gauge | Easy-to-read 1.5 inch Pressure Gauge 0-3000 PSI with indicator of when tank needs to be refilled | 17 feet long black 1/4 inch tubing | 2 plastic white washers | CGA320 Inlet, Maximum Inlet: 3000 PSIG | Solid Brass Body and Fittings — Warning: CO2 can cause injury (suffocation and Asphyxiation) or death, ventilate the area before entering. CO2 is stored at very pressure and a liquid CO2 is at cryogenic temperatures which can cause injury, burn, explosion, or death. CO2 should be handled by a trained professional and extreme caution should be taken when dealing with CO2. For safety always wear protective gear.