Diameter 36 mm The shield is clean, without stains. Timer works smoothly. New glass. Overlay index, two-color. The "parawater" designation means that the watch was not produced later than about 1973. The case number - 4-180721 - is in a later format, and the "52" was first made in 1965, so the watch does not. It may be earlier than the late sixties. From this we can safely say that the watch was made in 1969. Citizen staged similar events later with Parawater, the water-resistant watch. For its Trans-Pacific .Test in the summer of 1963, it placed 130 Parawaters in specially designed buoys and tossed them from the deck of a ship into the Pacific Ocean. Ocean currents carried the buoys and exposed watches all the way to the North American coast. The trip took about a year. When the buoys were retrieved, the watches were still working, thanks to Citizen’s waterproof “O” ring and its self-winding Jet Rotor, which wound the spring in response to the action of the waves. After presenting the first watch manufactured by Citizen, the beautiful pocket one, it is time for another milestone in watchmaking. This time, the first Japanese waterproof watch, THE PARAWATER! This makes it the grand, grand father of all the Citizen divers we all love so much! Please note that this was not intended for diving, but it was up to the task for swimming! In 1959 the company produced the first Japanese water-resistant wrist watch. This was the "Citizen Parawater". It was powered by the Citizen Cal. 920 (2B). It was produced with 19, 21 and 23 jewels. Soon after, the Parawater completed two trans-Pacific tests and one in the Sea of ​​Japan. The result, needless to say, was positive. "Water Couple" was changed to the universally recognized (an "boring" water resistant) somewhere around 1970-1973. Post register.