Drop-in resolution
Sellita SW290-1 vs Miyota 9015: do they swap?
Whether the Sellita SW290-1 and Miyota 9015 share a case, and what changes if you move between them.
Close in diameter, not a drop-in. The Sellita SW290-1 (25.60 mm x 5.60 mm) and Miyota 9015 (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 SW290-1 is the automatic small-seconds caliber with the sub-dial at 9, in dress and pilot watches. The Miyota 9015 is the slim premium Japanese automatic, a lower-cost slim alternative to the 2892 platform.
They differ in diameter (25.60 mm vs 26.00 mm), height (5.60 mm vs 3.90 mm), calendar layout (small seconds at 9, date at 3 vs centre seconds, date at 3). An automatic 11 1/2 ligne movement with small seconds at 9 and date at 3, at 25.60 mm x 5.60 mm. It shares the SW260-1 footprint but places the sub-seconds at 9, so each needs its own dial 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.