Citizen · Promaster · Ref CA0820-50X
What does a dive watch gain from a stopwatch?
A 45mm Eco-Drive dive chronograph with a green sunburst dial, a matching green bezel and a steel bracelet. Rated to 200m, timing to 1/5 of a second, and charged by light.
Movement
Eco-Drive B612
Citizen product page, CA0820-50X
Chronograph
1/5 sec, 60 min
Citizen product page, CA0820-50X
Water resistance
200m
Citizen product page, CA0820-50X
Case
45mm steel
Citizen product page, CA0820-50X
Crystal
Mineral
Citizen product page, CA0820-50X
Bracelet
Steel, safety clasp
Citizen product page, CA0820-50X
Two jobs, one case
A dive bezel and a chronograph measure the same thing, elapsed time, in two different ways. The bezel is coarse and can be read with gloves on. The chronograph is fine, down to a fifth of a second, and runs up to 60 minutes.
Citizen puts both on the CA0820-50X. The bezel turns one way only, as on the rest of the Promaster dive line, and the stopwatch runs off two pushers either side of the screw-down crown.
Caliber B612
B612 is the Eco-Drive chronograph caliber inside. Like every Eco-Drive, it charges a storage cell from light rather than running down a disposable battery, so the stopwatch, the date and the 12/24-hour display keep working without a service visit for a cell change.
That matters more on a chronograph than on a three-hander. Running a stopwatch is a real drain on a conventional quartz battery. Here, wearing the watch in daylight is the maintenance.
The green
Citizen finishes this reference with a sunburst green dial and a green bezel, and pairs it with a brushed and polished steel bracelet. The bracelet closes with a fold-over safety clasp with push buttons, which is what you want on a watch that is going in the water.
At 45mm the case is the largest of the three Promasters on this site. Citizen quotes that figure; we have not measured a unit ourselves. If your wrist is on the smaller side, the 44mm BN0150 diver is the closer fit.
Specs
- Reference
- CA0820-50X
- Case size
- 45mm
- Case material
- Stainless Steel
- Movement
- Eco-Drive Chronograph
- Caliber type
- Citizen Eco-Drive
- Water resistance
- 200m Diver
- Complications
- Chronograph, Date, Unidirectional Bezel
- Origin
- Citizen (Japan)
Specifications as published by Citizen. We research from manufacturer documentation and published sources rather than hands-on testing. Researched 2026-09-03.
Verdict
A 200m Eco-Drive dive chronograph on a bracelet, for people who want the stopwatch and never want to change a battery.
Strengths
- Light-charged B612 caliber, no battery changes
- 200m water resistance on a working chronograph
- 1/5-second chronograph to 60 minutes plus a 12/24-hour display
- Steel bracelet with a push-button safety clasp
Trade-offs
- 45mm is large, and the bracelet adds to the presence
- Mineral crystal, not sapphire
- No strap option in the box
- Not ISO 6425 certified like the BN0150 diver
Buy it if
A larger wrist that wants one watch for the pool, the boat and the office, with a stopwatch on hand.
Skip it if
Your wrist is under about 6.5 inches, or you want the simplicity of a three-hand diver.
FAQ
No. It uses Citizen’s Eco-Drive caliber B612, which charges from any light source. Citizen states no battery replacement is needed.
Sources
Researched and last updated 2026-09-03. We do not test watches in hand; every figure above is traceable to the manufacturer or the sources listed here.
Citizen Promaster Dive Chronograph CA0820
Reference CA0820-50X
Prices and availability change; the band above is a research figure, so check the current listing.
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