Sellita · Switzerland · Elaboré, Top, Chronometer
Sellita SW300.M1
The Sellita SW300-1 was developed in the early-to-mid 2000s as a direct response to Swatch Group's progressive restriction of ETA movement supply to outside brands, which began formally around 2002. Sellita, headquartered in La Chaux-de-Fonds, designed the SW300 family as a dimensionally identical substitute for the ETA 2892-A2, targeting Swiss watchmakers that needed a reliable thin automatic without ETA dependence.
At 25.6 mm wide and 3.6 mm tall, the SW300-1 matches the ETA 2892-A2's footprint exactly. One deliberate departure is jewel count: Sellita added four jewels to support the barrel arbor, bringing the total to 25 versus the ETA's 21. The movement beats at 28,800 vph (4 Hz) and is available in two sub-variants — the 'a' version with a quick-set date at 3 o'clock, and the 'b' version with no date and calendar components fully removed.
Around 2020–2021, Sellita overhauled the mainspring barrel assembly across the entire SW300 family, extending the power reserve from 42 hours to a typical 56 hours (minimum 50 hours per the official datasheet) without increasing the movement's height — a meaningful spec improvement over the original ETA in current configurations. Sellita documents Elaboré, Top and Chronometer/COSC ranges for the SW300-1 family; MING-specific SW300.M1 executions should be treated by the regulation and finishing stated for the individual watch rather than as a generic four-tier Sellita listing.
The specific notation 'SW300.M1' does not appear in Sellita's published technical documentation or in any major caliber database; Sellita's official designation for this movement family is 'SW300-1.' The '.M1' suffix is not an official Sellita caliber suffix and may reflect a brand-specific or supplier-assigned label applied by a watchmaker sourcing the base movement.
Hz
Jewels
Reserve
In catalog
Technical specification
| Manufacturer | Sellita |
| Origin | Switzerland |
| Type | Automatic |
| Beat rate | 28,800 bph · 4 Hz |
| Jewels | 25 |
| Power reserve | 45 h |
| Diameter | 25.6 mm |
| Height | 3.6 mm |
| Hacking seconds | Yes |
| Hand-winding | Yes |
| Date | No |
| GMT | No |
| Chronograph | No |
| Accuracy (stated) | Elaboré: middle rate 5 ±5 s/day, max divergence 20 s/day; Top: middle rate 4 ±4 s/day, max divergence 15 s/day; Chronometer: COSC criteria |
| Based on | ETA 2892-A2 |
1 model
Watches with this caliber
FAQ
Is the Sellita SW300.M1 automatic or manual?
The Sellita SW300.M1 is an automatic (self-winding) movement: a rotor winds the mainspring from the motion of your wrist, so it needs no battery. It can also be wound by hand via the crown.
What is the power reserve of the Sellita SW300.M1?
About 45 hours on a full wind — into a second day, so it keeps running overnight off the wrist. Power reserve is how long the Sellita SW300.M1 keeps running once you stop wearing or winding it.
Does the Sellita SW300.M1 hack (stop the seconds when you set it)?
Yes. Pulling the crown stops the seconds hand, so the Sellita SW300.M1 can be set precisely to a reference time before you push the crown back in. Hacking is what lets you sync several watches — or a watch and a phone — to the exact second.
Does the Sellita SW300.M1 have a date function?
No — the Sellita SW300.M1 has no date complication, so every watch built on it runs a clean, date-free dial. That suits symmetrical and vintage-style designs, and means one less thing to reset whenever the movement is allowed to stop.
How accurate is the Sellita SW300.M1?
The Sellita SW300.M1 is rated at Elaboré: middle rate 5 ±5 s/day, max divergence 20 s/day; Top: middle rate 4 ±4 s/day, max divergence 15 s/day; Chronometer: COSC criteria. That is a normal working range for an uncertified mechanical movement; a COSC-certified chronometer is held to a tighter −4/+6 s/day, and a watchmaker can usually regulate one closer. Real-world accuracy still depends on how each watch is regulated, worn, and serviced.
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