ETA 2801-2 caliber: dimensions and drop-in group

Used in: the hand-wound, time-only member of the 2800 family, in slim dress watches.

The manual, no-date base of the 2800 family at 25.60 mm x 3.35 mm. It shares the family diameter but has no rotor and no calendar, so it swaps only with the Sellita SW210-1 hand-wound caliber.

Drop-in group: 11 1/2 ligne hand-wound, no date (25.60 mm x 3.35 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.