This item is a 1/4" Air Bleeder Plug with Thin threads that can be found on the New style of a StaRite Dura-Jet DJ Series, Dyna-Glas/Dynamax, ABG, Dyna-Jet, TPE, Some StaRite Pool Multiports, Petair/...
This is a back mount pressure gauge with a 1/4" MPT Threaded Mount used on Swimming Pool and Inground Style Hot Tub Sand and DE Style Filters. Hayward, Pentair, StaRite, Purex,Jacuzzi,Pacfab, Filter...