This dual axis motor drive, with drive corrector capabilities, is designed for Celestron"s CG-4 mounts for tracking in RA and allows movement in DEC. It precisely controls the telescope"s tracking speed during long, timed exposures of celestial objects, producing the best possible image sharpness. Precision drive correctors are a must for those with a serious interest in astrophotography or CCD imaging. Four speeds are available -- 1x (sidereal), 2x for guiding, 4x, and 8x for centering.This precision, state-of-the-art DC motor drive operates from 4 D-cell batteries (user supplied). The hand controller module is very compact and fits easily in the palm of your hand. Motors for both axes are included, along with brackets, clutch and hardware.