Pinwheel Vipers are thin serpents, about as wide as a human finger, but can be as long as a man's arm. Their colour changes depending on what surface they are on; Doran mentions Pinwheel Vipers that are green, brown, and bright blue, to name a few. The snakes coil in a flat, pinwheel shape, which gives them their name.
Pinwheel Vipers live in the Plains territory alongside numerous other plants and animals. Their exact distribution throughout the territory is uncertain, but Doran has mentioned seeing the snakes near the River Broad, near Brighteyes flowers.