Gardiner Brown tuning fork. 128Hz, will produce notes of strong duration. Ideal for testing vibratory sensation associated with peripheral neuropathy and diabetes.
Liniger, C., Albeanu, A., Bloise, D. & Assal, J. P., 1990. The Tuning Fork Revisited. Diabetic Medicine, 7(10), pp. 859-864 – http://www.ncbi.nlm.nih.gov/pubmed/2149682