At 1.75mm thick, the RM UP-01 is the thinnest mechanical watch made. At that dimension the conventional architecture stops working entirely — there is no room for a stacked movement under a dial, so the calibre is laid out flat across the watch, and winding and setting move to keys on the face rather than a crown on the side. It is less a thin watch than a different answer to the question of what a watch is. What matters on examination: at this thickness the case is structural and flexing is the enemy, so any distortion is serious rather than cosmetic; the on-dial winding and setting keys, which are the reference's most unusual and least standard components; and complete original documentation. Any service must be Richard Mille. Confirmed through the desk. Maker: Richard Mille. Reference: RMUP01. Available through ELITA's private desk — verification review, discreet handling and storage. Price on request.