Cal. SW285-1 a is an automatic movement with moon phase, day/night indicator, and date from Sellita. Like other Sellita SW200 movements, it is based on the design of the ETA 2800 family, though ETA does not sell a direct competitor with the same functions. Sellita has produced this movement since 2019. Cal. SW285-1 M a is a hand-winding version.
The moon phase is indicated using a disc located at 6:00 on the dial and the date is located at 3:00. The day/night indicator is a pointer in a subdial at 10:00. This is very similar to Cal. SW285-1 b, which differs in that it uses a disc for the day/night indicator.
Sellita SW200 Technical Information
All automatic winding members of the SW200 family include bi-directional winding using a central rotor. The winding mechanism contributes to the overall thickness of the movement, adding 1 mm compared to the more-integrated winding system on the SW300/2892.
The Sellita SW200 design includes an extra jewel (bringing the total to 26) between the barrel and ratchet wheel. This serves mainly as a technical differentiator between the movements and is not an area of deficiency in the original design.
In 2008, Sellita modified the tooth profile of three wheels in the winding system to make them more resistant to shocks and wear. This resulted in the “-1” series of movements (e.g. SW220 became SW220-1). All other components are identical between these movements.
The similar SW400 movements are larger, at 31.00 mm diameter, but are otherwise similar in design and construction.
Sellita SW200 Family
| Complications | Hand Winding Calibres | Automatic Calibres |
|---|---|---|
| No Date | SW210-1 | |
| Date Only | SW215-1 | SW200-1 SW400-1 (31 mm) |
| Day-Date | SW220-1 M | SW220-1 |
| Date by Pointer | SW221-1 M | SW221-1 |
| Outer Day-Date | SW240-1 M | SW240-1 |
| Small Seconds at 6:00 and Date | SW216-1 SW261-1 M | SW260-1 SW261-1 SW461-1 (31 mm) |
| Moon Phase and Date | SW280-1 M | SW280-1 |
| Moon Phase, Power Reserve, and Date | SW285-1 M a SW285-1 M b | SW285-1 a SW285-1 b |
| Central Moon Phase and Date | SW288-1 M | SW288-1 |
| Small Seconds at 9:00 and Date | SW219-1 SW295-1 M | SW290-1 SW295-1 |