[Real Time Clock Chip]The DS3231RTC is used as a real time clock chip which keeps the time running even if the main power supply is off (with the help of a battery). [Complete Clock Calendar]Functionality Including Seconds, Minutes, Hours, Day, Date, Month, and Year, with Leap-Year Compensation Up to Year 2100. [Extremely Accurate]DS3231 16-pin memory chips - AT24C32 ,extremely accurate I2C real-time clock (), with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. [Two programm]Provides programmable time-of day alarms and a calendar can be set to a square wave output. Address and data are transferred serially through an I2C bidirectional bus. [Safe Enough]A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, provide a reset output. In addition, pin is monitored as generating a P reset. Working voltage: 3.3--5.5V Clock chip: High-precision clock chip DS3231 Clock accuracy: 0-40 Celsius, 2ppm accuracy, annual error is about 1 minute With 2 calendar alarm clocks Programmable square wave output The chip comes with a temperature sensor with an accuracy of 3 Celsius Memory chip: AT24C32 (storage capacity 32K) IIC bus interface, the maximum transmission speed is 400KHz (when the working voltage is 5V) Can be cascaded with other IIC devices. The 24C32 address can be modified by shorting A0 / A1 / A2. The default address is 0x57. With battery CR2032, to that the clock still moves normally after the system is powered off. Colour:blue Material:Plastic + Metal Size:38mm x 22mm x 14mm Weight: 8g Package Contents: 5 x DS3231 AT24C32 IIC Real Time Clock Module(With battery) Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.