The Drum-Stir is a simple but important improvement over screw-in or clamp-mount drum mixers. The Drum-Stir features a unique mounting system that’s easy to install and provides the most thorough mixing. With the mixer, the impeller can be centered in the drum instead of up against one side. The shaft and impeller don't hit the inside wall of the drum during installation. When the top of the drum sags, as they sometimes do, the impeller won't be pushed into the drum wall. See the drawings in reverse. (U.S. Patent No. 4,981,367
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