Inside the cup is a clear acrylic collar that's designed to hold the motor you specify. The clear acrylic allows visibility from above the motor carriage to the work surface where our LED light sources are located. For light duty work, inlay, marquetry and detail cutting this is a combination that brings the small-shank world of cutting tools into reach (and illumination)...all with the precision of a miniature milling machine. That's hard to beat.