Breitling · Chronomat and Chronomat

Breitling A10320101A1A1 vs Breitling AB0158101A1A1

12 published specifications differ between these two, and 2 are identical. Every figure below is what the manufacturer states for that reference; nothing is inferred from the other watch.

What differs

Specification	Breitling Chronomat Automatic 36, mother-of-pearl dial, steel braceletA10320101A1A1	Breitling Chronomat B01 Chronograph 42, white dial, steel braceletAB0158101A1A1
Case	Stainless steel, 36 mm	Stainless steel, 42 mm
Diameter	36 mm	42 mm
Thickness	9.68 mm	13.77 mm
Lug width	16.05 mm	20.05 mm
Water resistance	10 bars (100 m / 330 ft)	20 bars (200 m / 660 ft)
Dial	Mother-of-pearl, as stated in the page description	White, as stated in the page description
Crown	Non screw-locked, two gaskets	Screw-locked, two gaskets
Bracelet	Stainless steel bracelet, straight, 20 mm	Stainless steel bracelet, straight, 20/20 mm
Calibre	Breitling 10	Breitling 01 (Manufacture)
Power reserve	Approximately 42 hours	Approximately 70 hours
Jewels	25	47
Movement notes	Calendar shown in a dial aperture.	Chronograph to 1/4th second, with 30-minute and 12-hour totalisers. Calendar shown in a dial aperture.

What is identical

Worth knowing as much as the differences: these are the specifications you cannot use to tell the two apart.

Movement: Self-winding mechanical
Frequency: 28,800 v.p.h

Stated for one, not the other

These rows cannot be compared, because one maker publishes the figure and the other does not. An empty cell is a gap in the manufacturer's documentation, not a gap in the watch — and not a licence to fill it in from the other column.

Crystal	not stated	Sapphire
Bezel	not stated	Unidirectional, ratcheted
Case back	not stated	Screwed in (sapphire crystal)

What the differences cost you

Each note below follows from the published figures in the tables above — what they mean for intake, for a listing, and for the handover. Nothing here estimates a price or a margin.

These reach different buyers

42 mm on the AB0158101A1A1 against 36 mm on the A10320101A1A1. Diameter is a poor predictor of how a watch actually sits, but it is the field buyers filter on, so the two land in front of different people. Do not let one listing's photographs or copy stand in for the other.

A visible difference in how they wear

4.1 mm of thickness separates these, with the AB0158101A1A1 the taller at 13.8 mm. That is the difference between a watch that goes under a cuff and one that catches on it — worth a photograph from the side rather than a number in a table.

Do not describe these the same way

200 metres on the AB0158101A1A1 against 100 on the A10320101A1A1. Both are more than daily life asks for, so the number is a listing-accuracy question rather than a practical one: quote each watch its own figure, and remember that neither rating survives an unserviced case by itself.

One survives the weekend and one does not

70 hours on the AB0158101A1A1 against 42 on the A10320101A1A1. Below about sixty hours a watch left off the wrist from Friday is stopped by Monday. Wind both fully at intake and confirm they reach the stated figure — a short reserve leaves a tired barrel nowhere to hide, and it is the kind of fault a buyer reports in week two.

What to check on each

A10320101A1A1

Photograph the mother-of-pearl dial from at least three angles. It is a natural material whose figuring differs on every example, so a single flat image does not describe the watch a buyer will receive.
Look for hairline cracks and lifted edges in the nacre under a loupe, particularly around the date aperture and the applied markers where the material is cut.
Note that this page publishes no crystal, bezel or case back line. Do not fill those gaps from another Chronomat, and say in the listing that the maker does not state them.

AB0158101A1A1

Check the bracelet taper against the published 20/20 mm figure. This reference does not narrow toward the clasp, which is unusual and changes which aftermarket straps will fit.
Confirm the bezel ratchets one way only and holds firmly. A chronograph with a dive-style bezel invites the buyer to use it as one, so it needs to behave like one.
Test the chronograph under load for twelve full hours. The 12-hour totaliser is the register nobody exercises and the one a tired movement struggles with.

Sources

Not affiliated with Breitling. Specifications are read from each manufacturer's own published documentation on the dates shown and may change; the manufacturer's current documentation governs.