The present watch, offered here in overall excellent condition, is fitted with the Beta-21 electroquartz movement, developed by a consortium of watch companies, including Patek Philippe, at the Swiss Electronic Research Centre or CEH (Centre Electronique Horloger) in Neuchatel. It was the first quartz movement for wristwatches with analogue display and introduced at the Basel Fair in April 1970.
The first model of the series, reference 3587 was launched in 1969 and became reference 3597 in 1973. It was in production until around 1982. Reference 3603 was introduced into the market in 1972, also until around 1982.
The three models, the largest wristwatches ever produced by Patek Philippe, were available in different case, dial and bracelet colours and variations and are highly collectable timepieces.
References 3597 and 3602 as well as the Beta-21 are described and illustrated in Patek Philippe Wristwatches by Martin Huber & Alan Banbery, second edition, p. 332.