This Flush out fitting is designed to be installed in the wall of an RV wate tank. It is primary for black tanks but can also be installed into a gray tank. This is an aftermarket part that allows to clean and rinse out a black tank with out the need of putting a wand down the RV toilet to clean the tank out. This fitting is a simpler, cleaner, and more efficient way of cleaning out the black tank. To Install this fitting, you will drill a 1" hole in the end of the tank. Then apply a silicone or similar sealant that is advertised to bond to polyethylene. Insert the sprayer fitting into the tank with the sealant between the tank wall and fitting flange. Use 3 screws (NOT PROVIDED) to secure the flusher fitting to the tank, ***BE SURE TO NOT OVERTIGHTEN)***