ETA 2804-2 caliber: dimensions and drop-in group

Used in: the hand-wound date member of the 2800 family, the manual sibling of the 2824-2.

The manual-wind, date-at-3 version of the 2800 family at 25.60 mm x 3.35 mm. It adds a date disc to the 2801-2, so it needs a dial with a date window and swaps with the Sellita SW215-1.

Drop-in group: 11 1/2 ligne hand-wound, date at 3 (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.