... store 40000; 7,A built-in backup battery, can work 6 to 8 hours; 8,ER-691D ER-690D supports ID ... 125KHz; ER-691C ER-690C: 13.56MHz5,Read distance: ≥ 40mm;6,Read write time: less than 1second7,Storage capacity: maximum holds ... ,Transmission rate: 9600bps or 19200bps;12,Volume: L283.8*W190.6*H106 MM