Ronda 3520.D caliber: dimensions and drop-in group

Used in: a compact Swiss quartz chronograph at the 11 1/2 ligne size, in smaller 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-hander. Its chronograph train and sub-dials need a matching dial; it is a smaller alternative to the 5030.D.

Drop-in group: Ronda 3520 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.