It consists of two solenoid electromagnets on the same axis. Besides creating magnetic fields, Helmholtz coils are also used in scientific apparatus to cancel external magnetic fields, such as the Earth's magnetic field.
The question remains... A little bit of mystery is sometimes accepted. This is not just another zero point energy generator for sale to assist in meditation. You can feel the magnetic field going through your body!
Helmholtz Field Instruction PMT-500
Helmholtz Field used in Brain Reset Protocol - PMT-500
Helmholtz Field Instruction PMT-120