ETA 2671 caliber: dimensions and drop-in group

Used in: the small ladies automatic, in compact and slim cases with a date.

A miniaturised automatic at 17.20 mm x 4.80 mm, effectively a shrunken 2824. It shares nothing dimensionally with the 11 1/2 ligne core: it is its own small footprint, paired only with the slightly larger 2681.

Drop-in group: 8 3/4 ligne small automatic (17.20 mm x 4.80 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.