Seiko 4R35 caliber: dimensions and drop-in group

Used in: the branded Seiko date automatic behind many Presage and Prospex models.

The branded Seiko caliber that the NH35 copies, at 27.40 mm x 5.32 mm with date at 3. It shares the NH35 footprint and stem, so the two interchange within the 27.40 mm case.

Drop-in group: Seiko NH3x / 4R date footprint (27.40 mm x 5.32 mm, date at 3). 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.