3/8" Pipe Bulkhead Fitting
This fitting is used when you have a surface or wall you wish to connect a 3/8" pipe through neatly, without having a pipe just loosely "hanging" in a hole, where it could be easily moved around or even being damaged, if for example the hole is drilled through metal which may have sharp edges. Another example is if you want to run a pipe up from a cupboard through a countertop, the bulkhead fitting allows you to run the pipe up in a neat manner.