This Tuning Fork is made in Aluminium metal and anodized with GOLD coating.The Fibonacci tuning forks are an extension of the Solar Harmonic Spectrum. The first four Fibonacci tuning forks are also found in the Solar Harmonic Spectrum. These are C 256 1/1,C 512 1/2,G 384 2/3 and A 426.7 3/5. So if you have the Solar Harmonic Spectrum you already have four Fibonacci tuning forks. All you have to do to get the complete set Fibonacci tuning forks is to upgrade. The upgrade contains the following new tuning forks, and because they are not notes they are listed as Fibonacci number ratios. They are 5/8, 8/13, 13/21 and 21/34.