Frequency Technology Philip Stein currently offers two technologies in its best-selling timepieces – Electromagnetic Frequency technology utilizing electromagnetic fields, introduced in 2003, and Natural Frequency Technology, introduced in 2008. Both technologies work within the same beneficial key frequency of 7-9 hertz, which encompasses the chief resonant frequency of the natural earth and is a frequency that is harmonious and grounding to life. Studies have shown that both technologies have similar results, and consumers have reported better sleep, less stress, clearer focus and better concentration when wearing Philip Stein watches regardless of the technology.