Launch Rev Limiter Switch Box Change Your Launch Rpm On The Fly With This Controller. No Need To Dive Into The Prodata Software. For Use With Programmable Digital-7 Plus Only MSD IgnitionThis handy controller lets you change the launch rpm setting instantly for last second changes in track conditions. They plug into the RS232 computer harness and have two rotary dials for adjustments. Instantly changes the launch RPM setting of the Programmable Controls Two control dials, one for 1,000 RPM and another for 100 RPM Can only be used with programmable MSD Ignition Controls and Accessories Adjustable from 1,000 10,900 RPM in 100 RPM