Offered in excellent overall condition the present timepiece is idistinguished by its elegant and timeless design. The reference 5381BC features the Cal. 2121 - Introduced in 1970 Cal. 2121 was at that time the thinnest automatic movement with a date complication with a thickness of only 3.05 mm. Cal. 2121 was also used in several Royal Oak models notably the celebrated ref. 5402.