The Ball Engineer II Powerlight 72 Ref. NM2126C-S1C-BK is chronometer certified by the Official Swiss Chronometer Testing Institute COSC with power reserve of 72 hours. The watch can be taken off the wrist on Friday after work, left unworn for the weekend and put back on the Monday morning without the need to wind it up. It is equipped with 27 micro gas tubes for night reading capability. Anti-magnetic to 80,000 A/m with Mu-metal shield. Water resistant to 100 m.