The HUDY Engine Break-In Bench is the ultimate tool for easy, safe, and professional break-in of your .12/.15/.21 engine, and suits all bump-start SG crank engines. Allows for a controlled break-in process that reduces wear & tear on engine components and increases performance, reliability, and longevity. Constructed of top-quality components of tough aluminum and spring steel, the Break-In Bench comes partially assembled from the factory to get you running sooner. The Engine Break-In Bench is for use with bump-start engines with SG crankshafts, and may not fit RTR engines; customers may need to make own modifications so as to properly fit RTR engines. HUDY assumes no responsibility for any damages or injuries caused by any modifications to the Engine Break-In Bench or engines. Thick alu. base plate with integrated clamps allows quick, solid mounting on any workbench. Large protective propeller shroud safely covers the included prop. Includes pre assembled throttle linkage, universal engine mounts, large-capacity 125cc fuel tank, prop spinner, and all necessary hardware. Requires use of an electric drill (not included) to spin the prop. Break in your engine like the pros! Note: The break-in bench has been designed for .21 engines. However, most of the .28 motors currently available are a larger bore/stoke version of a standard .21, so they should fit on the bench.