ETA 251.264 caliber: dimensions and drop-in group

Used in: a Swiss quartz chronograph caliber, in analogue quartz chronographs.

A quartz chronograph at 25.60 mm x 5.50 mm sharing the 11 1/2 ligne diameter but far taller than a three-hand quartz. Its chronograph train needs a matching multi-subdial dial, so it is not a plain three-hand swap.

Drop-in group: ETA 11 1/2 quartz chronograph (25.60 mm x 5.50 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.