Trailed mixer-wagons vary in size from 5 m3 to more than 45 m3. Some self-propelled mixer-wagons can be even bigger than this for use on some industrial farming units. Displacement varies according to ration dry matter. More water means more weight. With dry (45% DM; dry matter) rations, a 14m3 mixer-wagon such as the one pictured, may contain 3 tonnes fully loaded, or enough for about 60 Holstein cows. A typical mixer-wagon commonly consists of: