The nFOCUS controller fits in the palm of your hand and provides two directions at two speeds with only two buttons using advanced logic control and 12V regulated output! Low speed is adjustable pulse width modulated (PWM) drive, providing full voltage torque for reliable low speed operation.Press the second button down while holding the first button down and nFOCUS digital logic control switches to high speed drive, to get you to focus quickly. nFOCUS avoids the problems with the focus motor controllers which adjust voltage to adjust speed, and thereby don't have the umph to turn the motor over at low speed. The nFOCUS whacks the motor with a full 12 volt, short duration pulse to overcome stiction at low speed operation, providing plenty of umph! It is amazing to see nFOCUS work, to see the focus change step by step till it's just right. No more coasting past then back past then past again. Uses 3 AA batteries (not supplied) for long life.. Compatible with Van Slyke Engineering, JMI, Celestron,MEADE LX200GPS microfocuser, Moonlite and others.