I am installing an Oxygenics shower head in my trailer. When I removed the old showhead I found that the fitting had a small opening to allow water thru - pic attached. Is this the usual fitting found in RVs? I?m assuming it?s for reducing water usage. But if the shower head is already reducing the water then this seems redundant. I don?t think it can be removed but not sure. Has anyone else seen this on their shower?