2 Prong Wartenberg Wheel

 A great medical device used for sensory stimulation, pain/pleasure play, and/or teasing. The wheel was designed to test nerve reactions as it rolled systematically across the skin. Contains two spinning pinwheel heads, one on each prong. 

Robert Wartenberg, namesake of the Wartenberg wheel, is sometimes incorrectly credited as its inventor. According to Wartenberg himself, the device was in widespread use in Europe when he lived in Germany. While he did not invent it, he found it "an indispensable part of the outfit for everyday neurologic practice," and recommended its use to his colleagues in the US. The Wartenberg wheel is also used as a sensation sex toy. It can also be used in conjunction with a violet wand electrical device.