Vintage Citizen 150m diver ref 4-540115 (from June 1969)

This is another used Citizen 150M dive watch. This legendary 150-meter dive watch from Citizen, with 21 jewels, model number 4-540115 (62-5370), was produced in the late 1960s and early 1970s. According to Mitka, it is not the first Diver by Citizen, but the first model to hit international markets in 1969 plus its mid ranged pricing made it a popular choice with professional and hobby divers alike, gaining the popular nickname: “Challenge diver” 

It features a robust stainless steel case, a bidirectional rotating bezel, and a screw-down case back, providing water resistance to 150 meters, which was standard at the time. The striking luminous hour markers stand out against the black dial, while the Benz hands are reminiscent of Rolex watches. The date display at 3 o'clock is uniquely designed. With a diameter of approximately 40 mm, it is both practical and aesthetically pleasing, remaining comfortable to wear even today. It is powered by a robust and reliable Japanese-made 21-jewel automatic movement. Like Seiko's 62MAS and 6105, this is a classic in the history of Japanese dive watches.

Due to its limited production and high market value, this watch is recommended for collectors and those seeking a vintage timepiece suitable for everyday wear. Luckily, a good friend parted with it! Thank you, Antonio!

The Citizen 4-540115 looks similar to the Citizen 150m diver Crystal Date, AUDS 52802-Y, except for the hands (i.e. Mercedes  hands vs the straight pencil hands.

Besides the differences in hands design, the back case designs are also different 

Left: Citizen 150m diver Crystal Date, AUDS 52802-Y (from May 1968)

Right top : Vintage Citizen 150m diver ref  4-540115 (from June 1969), 

Right Bottom : Vintage Citizen 51-2273 Diver Watch (from Jan 1980)

https://mitka.co.uk/citizen-150m-diver-6590163y/

https://serial-number-decoder.co.uk/citizen/citizen.htm?awc=aw&gad_source=1&gad_campaignid=1724404730&gbraid=0AAAAAD2uHpFhBlIgTdVBC24z4LAqqAVMl&gclid=Cj0KCQiA4eHLBhCzARIsAJ2NZoKHwLDhBVurE7fwsNoIu_zSL9LPL5NS6CzIqCDuBXnHe3Hrv4wikioaAjJ6EALw_wcB

https://sweep-hand.org/citizens-vintage-divers-1962-to-1980/