The EZ-Flo Autoinjector system allows you to fertilize while watering your plants. You mix a water soluble ferilizer in the tank. A simple dial on the lid of the tank allows you to choose your fertilizer rate. You them simply hand-water your plants, or use a sprinkler. Some of the water from your spigot goes through the first tube, into the EZ-Flo tank, picks up some of the concentrated fertilizer water in the tank and then exits through the second tube and flows out through your hose. This is a great way to fertilize your flowering plants throughout the growing season. You must put a back flow device on the end of your spigot, and then connect the EZ-Flo hose bib adaptor. This keeps any of the concentrated fertilizer water from flowing back into your home's plumbing system. These devices are often referred to as check valves and are available at Home Depot, Lowes, and plumbing supply stores.