百達翡麗，非常精細及罕有，鉑金長方形腕錶，配陀飛輪及十日動力儲存，型號5101，約2011年製

It takes much more than a cursory glance to realise that reference 5101 is a highly complicated wristwatch. In fact it is the first timepiece that combines two complications which are very difficult to accommodate in the confined space of a rectangular movement: two tandem mainspring barrels with 240 hours power reserve and a tourbillon precision regulator composed of 72 individual parts.

As is characteristic of Patek Philippe, hardly any signs on the outside of the piece reveal the complexity of its inner workings. Understated elegance has always been a hallmark of Patek Philippe but the tourbillon cage is in fact concealed for a very practical reason - the oil used to lubricate the mechanism is sensitive to ultraviolet rays and will decompose when exposed to daylight, thus losing its beneficial tribological properties. Extremely stringent standards are imposed on all Patek Philippe movements and even more so on tourbillon pieces.