Duncan The Drinking Bobbing Bird

This classic novelty drinking bird is a scientific wonderDip head in water and the liquid inside will flow upside down to make Duncan bobThis seemingly simple device uses the principles of thermodynamics to maintain a constant bobbing motionApprox. Dimensions (Packaging): 19 (H) x 5 (W) x 5 (D) cm / 7.4 (H) x 2 (W) x 1.8 (D) inches.