The Sellita SW330-2 is a Swiss made automatic watch movement with a second time zone display via a centrally located GMT hand. This caliber is a member of the SW300 family of movements that are based on the ETA 2892-A2 framework. The SW330-2 is an update to the original SW330 which was based on the 2893-2 (2892-A2 with a GMT module). At the time of this post, the SW330-2 appears to be the first and currently the only -2 evolution in the Sellita lineup.
Some of the topics covered in this caliber listing:
SW330-2 VS SW330-1 Differences:
The SW330-2 is a reworked version of the SW330-1 (which is an evolution from the original SW300). The SW330-1 became available to watch manufacturers in 2015, 7 years later the SW330-2 changes were announced in July 2020.
The calibre SW330-1 and SW330-2 are interchangeable, however, not all of the parts are. Keep reading…
Increased Power Reserve:
One of the main differences between the SW330-1 and SW330-2 is that the -2 has a longer power reserve of 56 hours on a full wind, compared with the SW330 and SW330-1 which is 42 hours. The newer barrel is referred to as RDM+ and is fully interchangeable with the old barrel. That means your SW330-1 powered watch can be upgraded to have a longer power reserve. Some brands may start to offer an option to upgrade your old barrel during a routine service. The new barrels were announced in December of 2020.
Old barrel part number: 020.010.00018
New barrel part number: 020.010.00065
Updated GMT System:
The GMT complication was also updated with an improvement to the quick setting feature of the GMT hand. At least 6 parts were redesigned for the SW330-2 causing the two calibers to not be completely interchangeable. Difference in parts include (new part numbers are in parenthesis):
Hour wheel 24h became a GMT wheel (031.049.00024 / 031.049.00031)
double toothed hour wheel became a single tooth hour wheel (031.046.00175 / 031.046.00176)
Intermediate date wheel (033.011.00044)
Hour indicator driving wheel became the intermediate corrector setting wheel (036.052.00001)
Corrector setting wheel (036.051.00018 )
Double corrector (053.204.00025)
Aside from these parts, everything else is interchangeable, however, all 6 of these parts must be used together and may not be used independently while mixing with parts from the older GMT system.
Sellita SW330-2 VS ETA 2893-2:
While the components are not 100% interchangeable, the cal. SW330-2 is essentially an upgraded clone of the ETA 2893-2. In fact, these movements are so similar that brands will often use them interchangeably and not disclose which one you are getting beforehand – although this is happening less often with ETAs being unavailable. If the watch brand happens to list both calibers and you prefer one over the other, be sure to make the request when ordering your watch new from the manufacturer.
Dimensions and beat rate are among the many similarities, but one notable difference is the jewel count and power reserve:
The SW330-2 has 25 jewels and the ETA 2893-1 has 21 jewels.
The SW330-2 has up to 56 hours of power reserve and the ETA 2893-1 has ~46 hours.
Here is an image comparing the two movements:
3 Grades and Accuracy Ratings:
There are 3 grades of the Sellita SW 330-2. The grades and main differences are as follows:
Spécial (Elabore) – Nickel balance wheel, adjusted in 4 positions, average rate of +/-5 seconds/day, maximum deviation of 20 seconds/day in all positions, isochronism of +/-15 seconds/day.
Prémium (Top) – Glucydur balance wheel, adjusted in 5 positions, average rate of +/-4 seconds/day, maximum deviation of 15 seconds/day in all positions, isochronism of +/-10 seconds/day.
To sum it up, the Premium grade will give you better timekeeping and a more refined look than the Special grade. You can learn more about Sellita grading here.
Interesting note: This may not be interpreted correctly, but Sellita seems to mention in the official documentation that when a lot of movements are purchased, only 95% of them must be within the specified limited.
“The limit values are subject to interpretation: 95% of the pieces delivered in a lot must be within the specified limits.” -Sellita
There are two main finishes from the factory: Standard and Refined. There is an option for custom or tailor-made finishing as well.
1 – Manual winding
2- Quick adjustment of the date, quick adjustment of the GMT hand
3 – Time setting, hacked seconds
Removing the crown and stem:
With the crown in time setting position, gently place a 1mm screw driver in the setting lever slot to press the detent button. Do not use tweezers unless you want to risk messing up the setting lever.
At the time of this post, replacement prices for a the SW330-2 were found online for around $330.00 USD.
Some SW330-1 main plates are still being used up despite being fitted with the new upgraded parts found on the SW330-2. If you have a transition movement like this, it will have a plus sign (+) near the Sellita logo and caliber number. Please comment below if you have a watch like this.
Editor’s note: Also causing caliber confusion are the watches like the 2023 Accutron Astronaut GMT (ref: 2sw8a002), where the official product description simply refers to the movement as being an “SW330”. Since it’s a new model, it’s safe to assume it is the SW330-2, but who know! And if the brands themselves can’t be bothered to inform potential customers with accurate specs, can you trust watch bloggers to do it? Apparently not, since most of the big blogs/magazines appear to have copied and pasted what Accutron gave them, instead of asking the (not so) tough questions like: which version of the SW330 did you guys use in this $3,500 USD watch?