The “I” actuator models feature an on-board software-based digital microcontroller. The controller is non programmable and will configure itself for one of 4 input modes depending on which leads are plugged in on power up. Available input modes are: RC servo, 0-5v, 4-20mA or PWM. The “I” series is available in both 6v and 12v models.“R” Series:This is a standard hobby-type remote-control digital servo interface (CMOS logic), compatible with most RC receivers. They are a 6v unit only.