Mixers measure out liquid concentrates (fertilizers, soil inoculants, pest control sprays, etc.) and mix them with the proper amount of water, so all you have to do is turn on the water and spray or irrigate! The Brass Siphon Mixer is for gardeners who do not use either drip irrigation or have low water pressure. The Add-it Proportioning Fertilizer Injectors and the EZ-Flo System are the next step up, accommodating low water pressure & drip irrigation. The Young Mixer-Proportioner is also easy to use, but is more appropriate for the frequent user who needs to be able to regulate the mixing ratio (a feature unavailable on the first two mixers). The Mazzei Injector offers the best value for the performance, but requires an assembly kit for installation.