Fibonacci Solar Harmonic Upgrade Tuning Fork SetIf you already have a Harmonic Spectrum Set, you can purchase this set of 4 as well to then work with all of them together. To help you, we suggest putting small stickers on the reverse so you know the order in which to use the tuning forks. Low C is 1 1 High C is 1 2 G is 2 3 A is 3 5 PLEASE NOTE: IF YOU DO NOT ALREADY HAVE AN ACTIVATOR FOR TUNING FORKS, YOU WILL NEED TO BUY ONE. We sell 4 different types of activators: Wooden mallet with a rubber