This handy controller lets you change the launch rpm setting of the Programmable 7 Ignition Control manually and at the last minute. The controller plugs into the MSD Programmable Ignition Control through the 9-pin harness. There are two control knobs, one for 1,000 rpm and another for 100 rpm the launch setting can be adjusted from 3,000 to 12, 500 rpm in 100 rpm increments. This unit is for use with Programmalbe Digital-7, Programmable DIS-3, Multi-Function Ignition Controlls, Multi Channel Controller, Midget Ignition and Pro Mag Controller