453Y-15-3 single stage regulators are designed for medium to heavy duty gas welding, cutting and heating applications. These single-stage regulators provide top performance in a wife variety of industrial and laboratory applications. Steel gauge protectors are color coded: green for Oxygen (GP32X) and red for Acetylene (GP32Y). Self re-seating external pressure relief valve on oxygen models. Conforms to CGA E-4 standard for gas pressure regulators. Stem-type seat assembly for more reliable performance. Forged brass body. 2-1/2" gauges for easy reading. 2-3/4" diaphragm.