Bulkhead Fitting - FPT x FPT - 1 in.
The 1 in. bulkhead fitting is made for pre-drilled tanks. It needs to be placed into a 1 3/4 in. Diameter hole in the tank to obtain the proper fit. Also for a proper seal the gasket that comes with the bulkhead must go between the bulkhead flange and the tank wall.
That Fish Place - That Pet Place