The standard shower head has a 1/2 inch IPT fitting on it, Now there are two types.
Hand held (Telephone type) heads designed to be hooked to the end of a flexible hose have 1/2 inch MALE connectors.
Wall Mount heads (Designed to go on the end of a pipe) have female fittings.
Oxygenics makes both types.
Both types are used both in homes and RVs.
And if you have the proper joiner or nipple, you can use any of them (If you get the right one (Wall or hand held) you don't need the adapter)
Home is where I park it!