Seeed 101020013 Grove - RTC(DS1307)

Seeed-Grove-RTC-Seeed-Studio-101020013-Seeed-101020013-Grove-RTC-DS1307-is-based-on-the-clock-chip-DS1307-and-supports-I2C-communication-It-uses-a-Lithium-cell-battery-CR1225-as-it-is-low-cost-and-very-energy-efficient-It-can-run-for-years-on-a-very-small-coin-cell-Seeed-101020013-Grove-RTC-DS1307-

Price: 6.73 from Rapid Online Rapid Electronics Ltd.