This is a rare Patek Philippe Nautilus 3700/001 from 1981 in steel and 18k yellowgold. The Gerald Genta designed first reference of the twotone Nautilus comes in outstanding good condition including it´s original certificate (sold in Mönchengladbach/Germany), the booklets and the red document-envelope. Also a copy of the last service-invoice (2320€) from Wempe in June 2016 will be delivered with. The original  dial is in flawless condition being protected by a very fat case in beautiful shape. The bracelet with 20 links has zero stretch like you can see on one of the images below. An iconic watch in awesome collectorscondition.