AX725 AX Pro Memory Series Stopwatches are professional timing devices with significantly increased functionality going beyond our tremendously successful Classic X (WOS) Series. The AX 725 has Exclusive "AOS" 4.5 Operating System with Twin Left-Right button operation feature, designed to give coaches, athletes, and timers the most precise timing available. All AX Pro Series Stopwatches are cased in Accusplit's distinctive, ergonomic designed "X" Case.