Seiko NH72 (TMI NH72A) caliber: dimensions and drop-in group

Used in: the hacking, hand-winding skeleton member of the NH3x family.

The hacking, hand-winding skeleton member of the NH3x family at 27.40 mm x 5.32 mm. It shares the NH70 footprint and stem but adds hand-winding and hacking, and like the NH70 it needs an open-worked dial.

Drop-in group: Seiko NH70 / NH72 skeleton footprint (27.40 mm x 5.32 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.