Tuning forks made predominantly from the most abundant element in the earth's crust. Aluminum - atomic number 13.

Standard alloy tuning fork, 1024 Hz. Made in the USA.
Aluminum alloy tuning forks. Made in the USA.
Standard alloy tuning fork, 2048 Hz. Made in the USA.
Standard alloy tuning fork, 256 Hz. Made in the USA.
Standard alloy tuning fork, 30 Hz. Made in the USA.