Miyota 90S5 caliber: dimensions and drop-in group

Used in: the open-heart member of the 90 series, showing the balance through the dial.

A 90 series caliber at 26.00 mm x 3.90 mm with an open-heart aperture that exposes the balance. It shares the 9015 footprint and dial feet but needs a dial cut for the open-heart window.

Drop-in group: Miyota 90 slim footprint (26.00 mm x 3.90 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.