Caliber reference
Sellita SW216-1 caliber: dimensions and drop-in group
The published footprint of the Sellita SW216-1 and which movements share it.
Used in: the hand-wound small-seconds caliber, in classic dress watches with a sub-seconds dial.
A hand-wound 11 1/2 ligne caliber with small seconds at 6 and date at 3, taller than the SW215-1 at 4.35 mm because of the separate seconds train. It needs a small-seconds dial and is not interchangeable with a centre-seconds movement.
Drop-in group: 11 1/2 ligne hand-wound small seconds (25.60 mm x 4.35 mm). 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.