When you do your regular clean out of your black water holding tank, you put a special clean-out wand down through your toilet into the black tank. That wand is attached to a length of garden hose. You can bring that hose in through the front door of the trailer, or you can attach a shorter length of hose to a faucet inside the trailer. As long as you have water on board, using the faucet is a great method because you can use hot water and you have much less messy hose to handle. This kit includes: one 1/2" x 6-foot hose and a bathroom faucet-to-hose adapter.