This part is an Air Injector Connector, HydroAir, 3/4"spigot x 3/8"barb.
This part receives a 3/4" Flex pipe in the spigot side that would measure about 1" Outside diameter and then a 3/8" Inside...
This part is a Jet Face, 1-3/4", HydroAir, Duo Blaster, 5 Scallop, Gray..
This jet has other parts the can be found in the below links and are sold separately: