Circle Track Digital Soft-Touch Hei Rev Limiter For Use With GM Style Hei Distributors On V8 Engines Only MSD IgnitionIn an attempt to keep costs down and racing close, many dirt track racing sanctioning bodies across the country institute a mandatory rpm limit in several classes. MSD has been in close contact with many tracks over the years and thanks to their input, as well as that of the racers, we are excited to introduce an rpm limiter designed for the Saturday night racer! The Limiter is encased in epoxy for protection against the abuse of dirt track racing.