Frederique Constant Watch Highlife Automatic Green FC-303G3NH6B. Rarely are watches certified by the COSC (Official Swiss Chronometer Testing Institute). This certificate is only issued to pieces that can guarantee perfect isochronism over a given time and at given positions – in effect, their ability to tell the time correctly, consistently and precisely, within the strict limits enforced by an ISO standard. The COSC is an independent Swiss organisation that only issues its chronometer certificates to these pieces after the watches have undergone numerous tests over several days. COSC certified pieces form an elite, a class of their own, intended for collectors for whom “Swiss precision” is an everyday necessity. The Highlife Automatic COSC was developed especially for them.