PROLITE is the main controller that can connect to 4 STR and/or 6 NAV.
NAV is navigation, the LEDs stays constantly on when connected to Prolite.
STR is strobe, the LEDs flashes when connected to Prolite.
The PROLITE is only for Strobes and contains 4 strobe (STR) ports.
The PROLITE-XL has 4 strobe ports and 6 (NAV) ports.
Each ascending number is more power than the last. For example NAV2 is almost twice as bright as NAV1. STR3 is more than twice as powerful as STR2.
The description of each light will indicate which craft it is best for.