Heuer wrist timer (60 min stopwatch). Untouched beautiful Valjoux 7710 movement signed Heuer. With Heuer signed Corfam original strap. Signature inside back cover: “Heuer-Leonidas SA, Swiss, Stainless steel back #175512”. Similiar strap and “wrist timer” is listed in the Heuer catalog from 1959 (ref. OnTheDash.com). Price then: $45. This one is from after the Heuer – Leonidas merger in 1964, so ca 1965. Large size for your wrist: 53mm!