For several decades, the “go-to” person for testing whether your energy device could put out more power than you were inputting was Walter Rosenthal. Trained as a Mechanical Engineer and a veteran of decades in the aerospace industry, Walt combined a boyish enthusiasm and curiosity that permeated his life and his passion for testing energy machines. This is what led him to his association over several years with the late Floyd Sweet during the formative years of the development of Floyd's legendary overunity device. In fact Walt built many of the accessories for this machine for Floyd, in addition to being an investor.