When focusing a telescope by hand, it is inevitable that you will shake the telescope, no matter how stable the mount. The motorised focus adjustment increases the comfort of your observation: not only will it be more comfortable to focus, but it will also be more accurate. Accurate focusing is particularly critical for photographic observation, but it is also useful for visual observation. A potentiometer on the hand control allows you to adjust the motor speed between 2.5 and 7.5 rpm.
The package includes adaptations primarily for SkyWatcher and Celestron Newtonian telescopes and refractors: the product can be used without modification on the manufacturer's 2" Crayford and 2" rack-and-pinion telescopes - other models require a home adaptation. (The product can only be used with 1.25" focal length tubes with a custom adaptation.)