![Rolex® calibre 640 balance adjust screw](http://perrinwatchparts.com/cdn/shop/files/no_image_available_1fc14079-7c58-46b2-af71-cb6839d89319_800x800.png?v=1704921741)
Rolex® calibre 640 regulator - flat hairspring
Genuine, Rolex ® part # 3538 balance adjust screw fits Rolex® 600, Rolex®620, Rolex®630, Rolex®635, Rolex®640, Rolex®645
* H. & W. Perrin Company Limited is independent of and not affiliated with or sponsored by Rolex®. Rolex® warranty does not apply to parts supplied by H. & W. Perrin Company Limited. Using generic parts may devalue your watch.