Automatic chronograph powered not by the classic Valjoux 7750, but by a Swiss calibre DUBOIS DEPRAX LWO 283, which is finer, and has been used notably in many TAG-HEUER cases. The markings US on the back of the watch, as well as the absence of any mention of it being "Swiss-made" on the dial, seem to indicate that the watch is from before the 1970s, as Hamilton moved to Switzerland in 1969. There are only very slight signs of wear. The high-magnification photographs attatched are an integral part of the description and will give you a more precise idea of the condition of the chronograph, which has a date function and a magnifying glass. The 40-ruby calibre has been examined by a professional watchmaker, who did not deem it necessary to be revised, and who has verified the oiling and has installed a new joint. But the water resistance is not guaranteed. Diameter: 36.5 mm without the crown, 42 mm from corner to corner, 12 mm in thickness. New 23-cm leather strap for wrists of 17-21 cm. The chronograph will be delivered with its original American box, which is also in very good condition, and will be sent by registered mail, carefully packed.