The SPORT DIVER REGULATOR is a single hose regulator, two-stage, demand regulator.
It was manufactured and marketed by E.R. Cross from 1948 to 1953.
During this period Cross owned and operated the Sparking School of Deep Sea Diving in Wilmington, California, and sold this unit, compete with an air cylinder and webbing harness through his Divers Supply company for US$79.95.
It was available at same time the first Aqua Lung systems arrived in America.