he Marathon General Purpose Quartz. The glass lens is made from sapphire crystals to provide ultimate: scratch resistance, overall durability, and clarity of dial viewing, all essential factors for military personnel. To assist in low light viewing, the dial uses tritium tubes for the hour indices as well as hour and minute hands. Tritium is a self-illuminating gas which will provide a 24/7 glow without the need for recharging. The ETA F06 is accurate to -0.3/+0.5 seconds per day and also includes an End of Life (EOL) indicator. The ELO will advance the seconds hand once every 4 seconds when the battery is low to inform you that a battery change is needed. Made in Switzerland.