Cal. 187 is a cam-switching chronograph movement produced by Hahn & Cie. of Landeron in the 1960s. It was part of the large Cal. 48 family, and features a date complication. Cal. 187 is closely related to the contemporary Cal. 248 and 348 and 14 ligne Cal. 254, which lack the date function.
The movement was set up for the date window to appear at the edge of the dial at 6:00, but some examples move the date window to 12:00 inside the dial.
The Dubey Schaldenbrand Index-Mobile was a rattrapante version of Cal. 187 which used a second spiral hairspring and a pusher located co-axially inside the crown.