Anti-scratch sapphire crystal with double anti-reflection treatment. All our watches are fitted with sapphire crystal. This is cut from a polished slice of solid sapphire that has been created by the fusion and crystallization of alumina. Sapphire is so hard that only a diamond can scratch it. Polished faceted hands and indexes are hand applied and coated with luminescent material for enhanced visibility. Safety push-button on the bracelet for comfortable use, prevents accidental opening. C.O.S.C. Chronometer for ultimate precision certified by the Swiss Office of Chronomentry. Each model that is officially certified as a chronometer is given a booklet and a C.O.S.C. card by TAG Heuer. The individual number printed on the card corresponds to the number engraved on the movement certified by the Official Swiss Chronometer Control. Each of these movements is a unique object that has been produced with the greatest possible care and is an authentic masterpiece of watchmaking. The C.O.S.C. Chronometer Certificate: a sign of very high precision and quality. TAG Heuer Automatic chronographs make it possible to measure times of up to 12 hours with an accuracy of 1/8th of a second. They are all fitted with very high-frequency Swiss movements and represent one of the great achievements in the long watchmaking tradition and history of the company. The principal characteristics of TAG Heuer automatic chronographs are reliability, simplicity of use and a highly legible display. They have a number of useful functions for professional and leisure sporting activities, as well as for everyday use: Simple time measurement & additional time measurement. Tachymeter scale on bezel for average speed measurement. The tachymeter indicates the average speed of a car, for example, by measuring the time taken to cover a given distance (a kilometer or a mile). Water resistant to 100 meters ensured by rigorous manufacturing standards and strict testing. Oversized screw-in crown - easy to hold and with two security gaskets reliable to 100 meters. Large display at 6 o'clock. Double sapphire crystal casebook fitted with six screws reveals movement. Permanent seconds at 3 o'clock appears in a Rotating System decorated with "Cotes de Geneve". Exclusive TAG Heuer rotating system with "Cotes de Geneve" finish.