A Master version of a tool has the advantage that this version has the possibility to read, write and adjust ECU software and therefore is a more complete tool. A Master tool is necessary for professionals who want to adjust the content of ECUs.

A Slave version only has the possibility to read and write software and is used mostly by less experienced tuners that don't adjust their own software. A Slave version always needs to be linked with a Master version of a tuning software supplier.