In 1937, Herb Sunshine, principal designer of electric instruments at Epiphone, introduced a new single coil pickup. It was state of the art at the time.
The “Master Pickup” with “Master Voice” tone control included individual, adjustable pole pieces.
The player could adjust both the height of the pickup as well as the magnetic pole pieces by turning individual screws. This way you could “dial in” your tone.
From 1937 to 1957 the Zephyr was Epiphone’s top selling lap steel. It features a “bikini” name plate logo and an aluminum hand guard.