Eztronics Corp&reg; 5 Pcs DS3231 AT24C32 IIC Precision RTC Real Time Clock Memory Module For Arduino Operating voltage :3.3 - 5 .5 V Clock chip: high-precision clock chip DS3231 Clock Accuracy :0-40  range, the accuracy 2ppm, the error was about 1 minute Calendar alarm clock with two Real time clock generator seconds, minutes, hours, day, date, month and year timing and provide valid until the year 2100 leap year compensation