Drop-in resolution
ETA 2836-2 vs Sellita SW220-1: do they swap?
Whether the ETA 2836-2 and Sellita SW220-1 share a case, and what changes if you move between them.
Interchangeable. The ETA 2836-2 and Sellita SW220-1 share the same 25.60 mm x 5.05 mm footprint and the same centre seconds, day and date at 3 layout, so one drops into the other's case with the correct dial and hands.
The ETA 2836-2 is the day-date sibling of the 2824-2, in dressier and tool watches that show the weekday. The Sellita SW220-1 is the Sellita day-date, the drop-in alternative to the ETA 2836-2.
Their published figures are the same to the tenth of a millimetre. Same 25.60 mm diameter as the 2824-2 but taller at 5.05 mm because of the added day disc. A 2824-2 will not fill a 2836 dial: the day window sits empty.
Matching diameter and height is necessary but not sufficient. A donor is only a true drop-in when the dial-foot positions, hand-hole sizes, stem length and calendar layout also match. Two movements can share a case and still need a new dial, re-broached hands or a cut-to-length stem.