Drop-in resolution
Sellita SW200-1 vs Miyota 8215: do they swap?
Whether the Sellita SW200-1 and Miyota 8215 share a case, and what changes if you move between them.
Close in diameter, not a drop-in. The Sellita SW200-1 (25.60 mm x 4.60 mm) and Miyota 8215 (26.00 mm x 5.67 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 SW200-1 is the primary Swiss alternative to the 2824-2, now the default in many microbrands. The Miyota 8215 is the low-cost Japanese workhorse, common in entry-level and fashion automatics.
They differ in diameter (25.60 mm vs 26.00 mm), height (4.60 mm vs 5.67 mm), beat rate (28,800 A/h (4 Hz) vs 21,600 A/h (3 Hz)), winding behaviour. Matches the 2824-2 to the tenth of a millimetre in diameter and height, with the same date-at-3 layout, so it is the standard drop-in donor when a 2824-2 is unavailable. It carries one extra jewel (26 vs 25).
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.