Thhe Mercury series was made from 1961 to 1971. They were non waterproof and used the #22, 24, and finally the 25 movements.There were even square and rectangular cases as well as the customary round ones.
Sprites were also made from 1964 to 1971 and were Water-RESISTANT. They used the #24 and 25 movements.
From the catalog numbers on the dial you can identify the series. Hope this helps. No expert here but I got the info from sec 4 of my service manual.