Sensitive sensor with diamond bearing and precise adjustment for high accuracies. The aluminium rotating vanes have stream-lined measuring heads made from plastic material (polysulfone). The shafts are, as standard, guided in protected, oiled beryllium-brass bearing sleeves and supported in tips made from special case-hardened steel. Particularly suitable for use in climatology. Equipped with snap-on measuring heads and, as a result, very easy to service.