These horns are similar to the Hella Supertone horns, but produce a slightly deeper tone. This horn kit uses a combination of one low tone horn (measuring 350Hz) and one high tone horn (measuring 415Hz) to project a powerful 114dB harmonic sound. The blue horn assembly is shielded by a yellow cage to prevent damage.
They can be found here http://cr3motorsports.com/Hella-sharp-tone-horns