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 part is a (1) 90 Ell 1 1/2" Street X 1 1/2"Slip with an 1/8" FPT hole in the side.. The 90 ELL receives a 1 1/2" fitting on one side which would measure 1 7/8" OD and then slips into a 1 1/2"...