DS1302 Real Time Clock Module Real-Time Clock Module For Ardui Product Description Module voltage compatible with 3.3V / 5V, can be connected to 3.3V or 5V SCM 3v 260mAh backup battery(not rechargeable batteries) Crystal oscillator 32.768KHz Working temperature 0°C to 70°C 4 positioning holes, diameter 3.1mm Size: 44 x 23 x 1.6mm