The Vaavud wind meter is made from high-quality, solid, unbreakable plastic. The maintenance-free low-friction bearings ensure that even the lowest wind speeds can be measured precisely. The free app displays the data in m/s, km/h, mp/h and kn. Length: 11.3 cm; Wind speed: 2 - 25 m/s; Compatible with Apple iPhone and Samsung Galaxy models. Includes: wind meter, neoprene case, conversion kit for Galaxy S II, instructions