COSC stands for "Contrôle officiel suisse des chronomètres". This label certifies the precision of time measurement under high requirements. All Tissot® COSC watches come with a 3-year warranty, guarantying not only the best accuracy in time, but also in longevity.
Tissot markets COSC-certified watches, which means they are approved stopwatches. This certificate is issued by the COSC (Official Swiss Chronometer Testing Institute), which spends 15 days conducting a battery of extremely stringent tests on the movements to check their accuracy, anti-magnetism and resistance to impact.