bought this to fix fuel drain back problem

When the fuel evaporates from the carb, it doesn't take a lot of cranking to get a fire.
If the fuel runs back farther than the fuel pump, the car must be parked on a incline.
That would require much more cranking to get a fire.
I would like to know what is inside that check valve though. All brass construction ?
Subscribed, good luck with it.