Seiko VH31 (SII) caliber: dimensions and drop-in group

Used in: the sweeping-seconds quartz caliber that mimics a mechanical sweep at low cost.

A quartz caliber at 23.30 mm x 3.45 mm whose seconds hand sweeps in quad-pulse steps to imitate a mechanical movement. It is a compact quartz footprint of its own and not a mechanical donor.

Drop-in group: Seiko VH sweep quartz (23.30 mm x 3.45 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.