Ladies and gentlemen start your engines! The Nubby Cover for Sphero supercharges your robot because it increases traction on land and speed in the water. Zip! Zip! Perfect for slippery, slidy or slanty surfaces. Constructed from a flexible, rubbery substance, it slips easily over your Sphero and remains in place even during demanding use. The Nubby Cover puts your Sphero in a category all its own. A must-have for any serious Sphero racer, trickster, gamester and dog chaser.