Drop-in resolution
Sellita SW220-1 vs Miyota 90S5: do they swap?
Whether the Sellita SW220-1 and Miyota 90S5 share a case, and what changes if you move between them.
Close in diameter, not a drop-in. The Sellita SW220-1 (25.60 mm x 5.05 mm) and Miyota 90S5 (26.00 mm x 3.90 mm) are near in size but differ in height, dial feet or layout, so moving between them means a new dial, hands and often a case adjustment.
The Sellita SW220-1 is the Sellita day-date, the drop-in alternative to the ETA 2836-2. The Miyota 90S5 is the open-heart member of the 90 series, showing the balance through the dial.
They differ in diameter (25.60 mm vs 26.00 mm), height (5.05 mm vs 3.90 mm), calendar layout (centre seconds, day and date at 3 vs open heart, no date). The day-date member of the SW200 family, dimensionally matched to the ETA 2836-2 including the 5.05 mm height and day-and-date-at-3 layout.
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.