Hamilton electric : wristwatch

Electromechanical watch with battery and balance as oscillator. Caliber Hamilton 505.
The watch is powered by battery, and no longer spring driven. However, the frequency of the oscillator remains the same as that function is still performed by the balance. Hamilton electric are first watches of that new type. Their production started in January 1957. They had caliber 500, while caliber 505 was used since 1961. The Pacer was in production from 1957 till 1969 and was the most popular model of Hamilton's Electric series. It had two standard dials – black and silver, case plated with two shades of 10 carat gold, as well as leather strap or bichrome metal bracelet.
American industrial designer Richard Arbib (1917 – 1995) designed in 1950s for Hamilton asymmetrical cases of new electric watches, e.g. Ventura, Everest and Pacer.