Drop-in resolution
Ronda 515 vs Ronda 513S: do they swap?
Whether the Ronda 515 and Ronda 513S share a case, and what changes if you move between them.
Same footprint, different calendar. The Ronda 515 and Ronda 513S share the 25.60 mm x 3.00 mm case fit, but the Ronda 515 is centre seconds, date at 3 and the Ronda 513S is centre seconds, no date, so a swap needs a dial cut for the new layout.
The Ronda 515 is a common Swiss three-hand quartz movement in mid-range quartz watches. The Ronda 513S is a three-hand no-date Swiss quartz movement at the 11 1/2 ligne size.
They differ in calendar layout (centre seconds, date at 3 vs centre seconds, no date), winding behaviour. A quartz caliber that shares the 25.60 mm 11 1/2 ligne diameter. It is not a mechanical donor: swapping a quartz Ronda for an automatic ETA changes power source, height and hand heights entirely. It swaps with the same-size Ronda 513S and 6203.B quartz calibers.
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.