HPI Savage is a line of 1/8th scale radio controlled monster trucks manufactured in Taiwan by Hobby Products International of Foothill Ranch, California USA. The original version was the now-discontinued and ready-to-run Savage 21 which served as the basis for the vehicles that came after. It featured a unique boxed chassis with parallel aluminum panels surrounding the transmission and drive axles, two-speed transmission, heavy-duty slipper clutch, eight oil-filled coilover shock absorbers, four-wheel-drive, HPI .21ci (3.4cc) pull-start engine with rear exhaust and a HPI 27 MHz three-channel pistol grip radio. A "reverse module," sold separately, mounts inside the transmission where it replaces an idler gear assembly. It utilizes the factory-installed radio's non-proportional third channel