Circa 1955-1956.
In 1956 Hamilton made roughly one-thousand prototypes of the model 500 electric movement for testing some of which were issued to employees for wear tests while others were kept in the lab for further analysis. A very few number of these prototypes came with clear backs to easily view the movement and were given to those with esteemed positions at the Hamilton Watch Company for testing as well. All wear-test cases were Titan cases with either a sealed or this very rare clear back. This was so that a board member, executive or lab tester could see the movement operating without taking the back off. This rare timepiece comes in a 10K yellow gold-filled case with 14K gold numerals and markers with a pearled track on a white dial. Since this is a prototype wear-test model, the word Electric is not present on the dial as seen in the later Titan dials. Again, the clear back allows an unobstructed view of the Model 500 electric movement equipped with a fresh battery. This watch measures approximately 35mm wide x 43mm from lug end to lug end.
In 1956 Hamilton made roughly one-thousand prototypes of the model 500 electric movement for testing some of which were issued to employees for wear tests while others were kept in the lab for further analysis. A very few number of these prototypes came with clear backs to easily view the movement and were given to those with esteemed positions at the Hamilton Watch Company for testing as well. All wear-test cases were Titan cases with either a sealed or this very rare clear back. This was so that a board member, executive or lab tester could see the movement operating without taking the back off. This rare timepiece comes in a 10K yellow gold-filled case with 14K gold numerals and markers with a pearled track on a white dial. Since this is a prototype wear-test model, the word Electric is not present on the dial as seen in the later Titan dials. Again, the clear back allows an unobstructed view of the Model 500 electric movement equipped with a fresh battery. This watch measures approximately 35mm wide x 43mm from lug end to lug end.