This top-of-the-line set is calibrated for decay rate per second and for frequency. Features six forks at 128Hz, 512Hz, 1024Hz, 2048Hz, and 4096Hz. Used for all traditional and newer tests including the Weber, Rinne, Bing, Schwabach, Binaural Balancing, Central auditory Training(localization,spatial),Tinnitus Matching, Transcranial/Internal CROS, and Soundfield Testing. A must for hearing health professionals