Function Generators are electronic test equipment and should not be considered Rife machines. Dr. Rife never wanted his name put on any equipment (listen to Rife's words on this topic by pressing play below:)
The use of function generators for what Dr. Rife was doing began in 1957. John Crane and John Marsh took an off-the-shelf function generator and changed the face plate as shown in the photos below

We make no medical claims at all on this site for the GB-4000. We also make no medical claims for what Dr. Rife said he was able to accomplish using frequencies. The frequencies that he said would devitalize microorganisms are only listed for your information and do not constitute medical claims by us. Everything on this site is for informational purposes only. Any common function generator of the proper frequency range can output the same frequencies Dr. Rife used. The GB-4000 is not to be considered a Rife machine. It is a sweep function generator. It is sold as electronic test equipment. In fact you will notice the faceplate states that it is a 20 Megahertz Sweep function generator. What people do with it is their own personal business and responsibility.