Ronda 6203.B caliber: dimensions and drop-in group

Used in: a Swiss quartz caliber with a second time zone display in GMT-style watches.

A quartz movement at 26.00 mm x 3.30 mm carrying a dual-time (second time zone) function alongside the date. Its extra 24h train means it needs a matching multi-hand dial and is not a plain three-hand swap.

Drop-in group: Ronda 11 1/2 quartz dual-time (26.00 mm x 3.30 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.