1 1/2 inch dia outer thread, Thread = 12 TPI, Center thru hole = 3/8" pipe thread, Material = ASA plastic that is oil resistant.   Perfectly smooth running threads.  O-ring gasket included.   This is for one part only.   3/8 inch pipe nipple is not included. 
 
The maximum usable temperature for ASA (acrylonitrile styrene acrylate) is generally considered to be around 93°C (199°F), meaning it can withstand sustained temperatures up to this point without significant deformation or degradation in properties; making it a good choice for applications requiring moderate heat resistance.