Gentec 153 Series Single Stage Regulators are specially designed for heavy duty gas welding, cutting, and heating applications. These regulators are ideal to use for steel fabrication, ship building, metallurgical and chemical industries. 5/8in-18RHF, Gas: Carbon Dioxide. 2-1/2in gauges for easy reading 3- 1/4in stainless steel diaphragm for accurate pressure delivery Delrin cap bushing for smooth adjustments Stem-type seat assembly for more reliable performance Forged brass body and housing cap Self re-seating external pressure relief valve on oxygen, inert gas, air, CO2, and hydrogen models Sintered bronze inlet filter Steel Gauge Protectors are color-coded: green for Oxygen GP31X and red for Acetylene GP31Y Models Weight: 4 lbs 13 oz UL listed