Relief/Filler Vent Plug - Thread Size 1/4-18 PTF Dia Hex Flats (In.) 9/16 in Height 0.59 in Top Cap Dia (In.) 7/16 in Base Square (In.) - Overall Length (In.) 1 1/8 in Max Operating PSI - PSI 1-5 Max Operating Temp - Filter 20 Micron Vacuum (In. Hg) - Brass and Plated Steel Automatic Reset for Continuous Duty Dual Purpose Relief or Filler Vent Plugs can be Used for Gearbox Housings and Bearings to Eliminate Excessive Pressure