Ronda 513S caliber: dimensions and drop-in group

Used in: a three-hand no-date Swiss quartz movement at the 11 1/2 ligne size.

The no-date three-hand member of the Ronda 500 quartz family at 25.60 mm x 3.00 mm. It shares the 515 footprint and stem, differing only by the absence of a date, so the two swap within a matching dial.

Drop-in group: Ronda 11 1/2 quartz three-hand (25.60 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.