Drop-in resolution
Ronda 515 vs Ronda 505: do they swap?
Whether the Ronda 515 and Ronda 505 share a case, and what changes if you move between them.
Close in diameter, not a drop-in. The Ronda 515 (25.60 mm x 3.00 mm) and Ronda 505 (25.60 mm x 3.10 mm) are near in size but differ in height, dial feet or layout, so moving between them means a new dial, hands and often a case adjustment.
The Ronda 515 is a common Swiss three-hand quartz movement in mid-range quartz watches. The Ronda 505 is a three-hand Swiss quartz caliber in the 500 family, at the 11 1/2 ligne size.
They differ in height (3.00 mm vs 3.10 mm), calendar layout (centre seconds, date at 3 vs centre seconds, date at 3, small seconds sub-variant). 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.