Citizen Promaster BN1024-01Z Diver 300m with Helium Valve Garnet

BN1024-01Z | The Heir to the First Diver in Garnet

Citizen Promaster BN1024-01Z 300m with helium valve, ISO 6425 Annex A certification for saturation diving and Eco-Drive E365 caliber with 365 days of autonomy.

This Citizen Diver is not a watch for everyone. It is large (46 mm, 16.3 mm thick), has significant weight and an imposing presence.

It is made for diving professionals, with saturation diving certification, helium valve and 300 meters of resistance. It inherits the iconic design of the popular 200m BN0156, but adds the helium valve and saturation certification, making it the natural heir for those who need maximum professional performance.

It carries the Promaster seal: Citizen's line made for those who need an instrument, not an ornament.

You can view more Promaster watches in our category; if it's not what you were looking for, we also have hundreds of watches from the Citizen brand itself in our store.

If you are comparing the price of the Citizen BN1024-01Z with other ISO 6425 certified professional divers, here are the features of this Promaster with helium valve and annual maintenance-free autonomy.

Promaster Construction: steel, 4 mm sapphire and a notched bezel

The case is made of steel. The crown is at 4, protected, as in classic Promasters (direct heir to the BN0156). The bezel is unidirectional, 120 clicks, with a steel insert. It is notched, as it should be: so you can grip it with neoprene gloves and turn it without hesitation. The feeling is solid, precise, like a tool. It's not for play: it's for counting minutes underwater.

The crystal is flat sapphire with anti-reflective treatment. In a diving watch, this is key: it doesn't scratch easily and is readable underwater without reflections. To withstand 300 meters, the crystal is 4 mm thick. It's not an ornament, it's a wall.

The dial is garnet, with a subtle gradient that gives it depth. There is also the black variant. The indexes and hands are large and have a generous layer of luminescent material. In the dark, it can be read at a glance. No need to strain your eyes.

Part of its components are made of recycled materials. It's no coincidence: Citizen, with its Promaster line, says 'I preserve the sea, that place so incredible and necessary to maintain'. And it says it with facts, not slogans.

The strap is made of BENEBiOL, a plant-based polymer developed by Mitsubishi. It is resistant to hydrolysis, meaning it doesn't dry out or crack with salt water, sun and intensive use. It has a necessary extender to wear it over a wetsuit.

The case back has a detail for those who understand: the engraving of a diving helmet, the universal symbol of the professional.

It runs on light. The E365 caliber is Citizen's latest advancement in Eco-Drive technology: with a full charge, this diver runs for 365 days without needing to see the light. It is no coincidence they call it E365. For a professional diver, that means 0 maintenance and more time to do what they like: going down there.

300 certified meters, helium valve: what separates a Promaster from any other diver

Resistant to 300 meters with ISO 6425 certification, including the demanding Annex A for saturation diving. It is also anti-magnetic up to 4,800 A/m.

Furthermore, the Promaster BN1024-01Z has a helium valve. This is not for a weekend dive, but professional divers who work at great depths breathe helium, and this gas seeps into the watch. That's why it has a helium valve: so that, when ascending, the gas can escape without bursting the crystal. If you don't dive like that, you won't use it. It is the proof that this is a real instrument, not an ornament.

Like any professional diving instrument, it is advisable to rinse it with fresh water after use in the sea.

Who is this watch for?

• Professional diver

• Advanced enthusiast who wants real certification

• Promaster collector

• User looking for a “maintenance-free” diver

Frequently Asked Questions about the Citizen Promaster

What does "Annex A for saturation diving" mean? Do I need it?

It is the highest level of ISO 6425 certification for diving watches. Not all watches that withstand 300 meters have it. This BN1024-01Z does —which includes, of course, the 4,800 A/m magnetic resistance required by the standard.

In short: it means the helium valve is tested for professional saturation diving conditions, the real deal, like spending days in hyperbaric chambers. If you don't dive like that, you won't use it. But if you work down there, you need it. And this Citizen has it.

Is it very large for a wrist under 18 cm?

The case measures 46 mm in diameter and 16.3 mm thick. The weight is 161 g according to Citizen.

On paper it seems imposing, but several buyers comment that "it looks smaller than it is" and that "it wears very well on the wrist almost hiding its large size" thanks to the hidden lugs design. If you have a small wrist, the ideal is to try it on, but it is designed to be usable even for those who don't have a professional diver's wrist.

How often should the battery be changed? Or does it not have one?

It does not have a battery. It is Eco-Drive, charged by any light source (natural or artificial). A full charge gives it 365 days of autonomy. When the charge is low, the second hand starts moving in two-second intervals to warn you. You will never have to open it to change batteries.

Why does it have a helmet engraving on the back?

The case back is engraved with a traditional diving helmet, the universal symbol of professional diving and saturation certification. It's a detail for those who understand: a seal that this is a real instrument, not an ornament. On the side (at 9 o'clock) it is also engraved with "300m PROFESSIONAL DIVER'S".

In short: is it for me or is it too much watch?

If you are looking for a watch for dress or for the office, it might be too big for you. But if you want a real diving instrument, with professional certification, which also has a spectacular dial (gradient garnet) and technology that needs no maintenance, this is your watch. And if you don't dive, it's also worth it: you get a Promaster with 365 days of autonomy, sapphire, helium valve and a brutal personality.

In short: if the black Citizen BN1024-01E is sober, the garnet one has personality. You choose how you want to go down to 300 meters and back. It is not an “aesthetic” diver. It is a certified instrument. And that, in this price range, makes the difference.

Other models that may interest you

The Citizen BN1024-01Z, with its helium valve and true professional tool appearance, is the technical heir of a lineage. But the family of large Citizen divers has more members. Before this evolution with saturation certification, a professional 300-meter line already existed: models that dispense with the helium valve but maintain size, robustness, and presence. The community affectionately calls them "Ecozilla" (or "ashtrays" because of their shape).

If you are looking for that imposing presence of 48.2mm and professional diving performance without the complexity of saturation, this is your family.

The BJ8055-04X is the most eye-catching of the three. Its dial is an intense green with a gradient reminiscent of deep sea depths. Plus, it has an extra: in the dark, the dial glows completely, not just the indexes. It's a little party on your wrist when the light disappears.

Then there is the special edition, the one that goes a step beyond the design and the nickname: the BJ8056-01E "Godzilla". This is not a watch, it's a collector's piece. Citizen launched it to celebrate the "King of the Monsters" and the anniversary of the Promaster. It has the same size, the same construction, but the black dial hides a laser camouflage pattern simulating Godzilla's scaly skin. And if you turn it over, the beast is still there: the case back is engraved with its footprint. Fans dubbed it "Ecozilla" for a reason. It is for those who understand the myth.

Finally, the BJ8055-04E. Black and Blue. Just as professional as its brothers, but without stridency. Its black dial, with blue touches on the strap, is designed for those who want a 300-meter instrument that doesn't scream, but simply works. It also has the case back with the diving helmet, the seal of those who take it seriously. It is the original "ashtray," but updated.

All share the essentials: 48.2 mm case, thick domed mineral crystal, and a rubber strap with extender to wear over the wetsuit. If the BN1024-01Z is a Swiss army knife of professional saturation diving, the "Ecozilla" are the hammers: solid, reliable and with a lot of character. You decide with which one you want to go down to 300 meters and back.

Buy with official warranty

This Citizen BN1024-01Z is 100% original. We are an official Citizen dealer, with international warranty (2 years, extendable to 3 in Spain) and access to its technical service. Oh, and it comes in a box shaped like a yellow tank. It's not a real one, but when you see it, it will take you to the boat.