440Hz + A Tuning Fork. Aluminum tuning forks for demonstrating the relationship between sound and vibrations, the energy transfer between resonating systems and as a source of standard frequencies. Milled from non-rusting, non-magnetic aluminum bar stock. Plain shank form. Stamped with the musical scale note sounded by the fork and the frequency in Hz at the base of the tine of each fork. It measures 6 & 1/4 inches long, 7/8 inches wide and 1/4 inch thick.