The Tanaka 6688819 Gear Case Assembly helps transfer power from the drive shaft to the cutting head for compatible Tanaka string trimmers and multi-task tools. It works by housing the internal gears and bearings that convert rotational power into efficient cutting performance, supporting smooth operation and dependable power transmission. Made to replace a worn or damaged gear case as... https://www.wholetoolbox.com/tanaka-6688819-gear-case-assembly/6688819.html