Citizen Eco Drive BN4021-02E Altichron watch Review

Citizen is a well-known brand in the world of watchmaking, renowned for producing high-quality timepieces with impressive features. The Citizen Eco-Drive BN4021-02E Altichron is no exception.

Its rugged design and advanced technology make it a popular choice among outdoor enthusiasts and adventure-seekers alike. With its altimeter, compass, and chronograph functions.

This watch is built to withstand the toughest of conditions and provide accurate readings no matter where you are. In this review, we will take a closer look at the Citizen Eco-Drive BN4021-02E Altichron and explore its features and capabilities in greater detail.

Honestly, it’s one of those watches that you fall in love with at first sight, and that doesn’t let you down when you get deeper into the relationship.

The good thing about Promaster Altichron watches is that they are very capable: they measure pressure and altitude and have an electronic compass… perfect for your best adventures… but you have to be careful with one thing: you can stare at the face of this watch … it bewitches you… and you will not enjoy the landscape 🙂

Let’s see how this watch behaves in our review, although you can already imagine that he has passed the exam with flying colors. We have included it among the best Citizen watches for men.

Page Contents

Citizen Eco Drive BN4021-02E Altichron watch: features and design

Watch Citizen Promaster Altichron Bn4021-02e Men´s GPS Black
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Watch Citizen Promaster Altichron Bn4021-02e Men´s GPS Black
  • Case material titanium
  • Band width: 24 millimeters
  • Water resistance: 200 meters

  • Eco-Drive J280 analog movement
  • Altimeter from -300 to 10,000 meters, with two indicator needles: the main one and the one located on the 9-hour subdial.
  • electronic compass
  • Charge reserve indicator.
  • Calendar.
  • Water resistance WR 20 bar.

The special Citizen watch for adventurers, trekking, or mountaineering. The spectacular sporty design is offered by the Japanese brand. You fall in love as soon as you see it.

  • Reading the dial can be somewhat tricky at first, so it is best to read the manual calmly as soon as you take it out of the spectacular box where Citizen has placed it. Worth.

At first glance we realize a few important things: it is a watch that has solar charging (Eco Drive), an electronic compass, and an altimeter, it has an atmospheric pressure sensor (left to the center) and you can submerge yourself in the water with it ( 200m bar). It would only need the radio control to synchronize the time and a sapphire crystal to be perfect. It always happens… there are no perfect situations with Casio, Citizen, or Seiko watches.

But what stands out to you the most about this watch is its tremendous design: it’s nothing like anything you’ve seen before: Citizen has pulled off a winning horse with this model (and with the Aqualand Eco-Drive Promaster BN2024-05E diver).

It does not have any digital screen, it is completely analog, and on the dial, we are going to find a beautiful, colorful dial with large indices… with many hands, with one dial after another…

It looks like a pilot’s watch. Then we see all its functions and how to distinguish what each dial and hand does.

  • You will find the best of Japanese technology inside not only this watch but also the best of an original and avant-garde design.

It has two large crowns on the right side and two huge buttons on the left side (the center is the sensor). With these 4 elements, you will have to control the entire clock. Luck! 🙂 No Bluetooth and mobile app like many Casio G-shock or Edifice models. Old school to power in the Citizen Eco Drive BN4021-02E Altichron.

The style of the strap also stands out: it is made of rubber (Liquid Rubber polyurethane), it is very comfortable and it is long. It has a very sporty design. And you realize that you can’t put the watch upright on a table, a nice feature that G-Shocks have: it serves to protect the watch movement (analog Eco Drive J280) and all its electronics. If it falls to the ground, the strap forms part of the watch’s protection due to the shape it takes.

  • The case is made of titanium (Super Titanium DLC) and shows both quality and design. It is 49.5mm, which means that it is quite a large watch. It has a beautiful polish. The watch is very light with only 98.8 grams of weight.

On the back, we find all the data of the watch. It is also polished. How does the lumen behave? Let’s see the photos:

The hour and minute hands and indices have excellent lumen (sorry for the photos). So does the arrow mark on the edge of the dial. It does not have an LED light. We can do without it.

Citizen Eco Drive BN4021-02E Altichron: how it looks on the Wrist

Citizen Eco-Drive BN4021-02E Altichron review

I have a 19cm wrist and the truth is that it is on the limit between looking good and looking gigantic. You have to get used to it at first, but then there’s no problem.

Because the strap is so comfortable (as is the case), wearing this Citizen watch is bliss. He becomes your best friend on getaways.

Citizen Eco Drive BN4021-02E Altichron: functions

It is a perfect sports watch to go out into the field and go on an adventure.

First: it has Citizen Eco Drive technology, which means it charges from the sun (faster) or any light source (slower). This implies that its maintenance is very low. If it had a radio control to always have the exact time… it would be perfect (and sapphire crystal to be more resistant)… but it is quite precise. Don’t worry too much.

The problem that you may encounter with this watch at first is that you have to know how to use its different functions: Altimeter, electronic compass or even set the time… and for this, you have to understand what each needle is for:

  • The white hands give you the hours. The simplest.
  • The orange and yellow hands when measuring altitude: orange (100m hand -Indication range: ‒300mm to 900m-); Yellow (Hand 2.5m -Indication range: ‒97.5 m to 97.5 m-). The small hand on the left dial also indicates higher altitudes (Indication range: ‒300 m to 10,000 m). You can calibrate the altitude based on your position. You can measure the difference in altitude.
  • The orange hand functions as a compass in “compass” mode. You can calibrate the compass to give you more accurate measurements. You can calibrate the reference position. If there is abnormal magnetism, the hand will point to a small red dot at the bottom of the dial inside.

And each hand refers to the numbers of a certain dial (each one has a different scale). In the first pages of the manual, you have some good explanatory diagrams.

The small dial on the left indicates the winding of the watch and the upper right crown allows the scale of the rotating inner bezel to be rotated. The square of the date is at 3. Between the two buttons on the left, we have the atmospheric pressure sensor.

With the crown on the right (lower) you change the time and date (you have two positions).

By pressing the yellow B button you measure the altitude. By pressing the red button on the left you start the compass.

  • If the second-hand starts to move in two-second intervals, run to put your watch under the sun’s rays. It has a low charge. In 3 minutes you have a charge for a day and in 35 hours a full charge.
  • In the manual, you can find the accuracy range of the compass and altimeter.
Operating temperature range‒20°C to +60°C
Time accuracyAverage Monthly Accuracy: ±15 seconds when used at normal operating temperatures between +5°C and +35°C
FunctionsSolar power (Eco Drive)
Power reserve indication (in 4 levels)
Overcharge prevention
Insufficient charge warning (2-second interval movement)
Altitude indication Altitude
calibration Compass
indication Compass
calibration Compass
position check compass/altitude indication hands reference and setting function

Conclusion: Is it worth buying this Citizen watch from the Promaster range?

Worth. It’s like feeling first love… with a watch. It is a very attractive watch, the strap is really comfortable and it looks great if you have a medium-sized wrist.

The titanium in the case makes the watch very light and gives it a tremendous look. It is a solar-charged watch, so you forget to change the batteries.

It would only need to be radio-controlled to always have the exact time and for the sphere to have a sapphire crystal.

In favor:

  • The precious sporty dial design
  • titanium case
  • Sensors: compass and altimeter
  • Very comfortable and colorful strap
  • Very light and resistant


  • It does not have a radio control to adjust the time
  • The crystal is mineral and not sapphire.
  • You need to understand the different functions of the dials on the dial

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