Drop-in resolution
Ronda 505 vs Ronda 585: do they swap?
Whether the Ronda 505 and Ronda 585 share a case, and what changes if you move between them.
Close in diameter, not a drop-in. The Ronda 505 (25.60 mm x 3.10 mm) and Ronda 585 (25.60 mm x 3.60 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 505 is a three-hand Swiss quartz caliber in the 500 family, at the 11 1/2 ligne size. The Ronda 585 is a small-seconds Swiss quartz caliber, in dress quartz watches with a sub-seconds dial.
They differ in height (3.10 mm vs 3.60 mm), calendar layout (centre seconds, date at 3, small seconds sub-variant vs small seconds at 6, date at 3), winding behaviour. A 500-family three-hand quartz caliber at 25.60 mm x 3.10 mm, sharing the 515's diameter and stem. It swaps within a matching three-hand dial with the 515, 513S and 6004.B.
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.