The RTC DS3231 module is a real-time clock that enables accurate time-keeping with minimum fuss. It uses a DS3231 IC, which is an extremely accurate RTC chip with a built-in 32 kHz crystal oscillator. The chip also features a basic temperature sensor and alarm clock capability.The RTC module uses a standard I²C interface and can easily be interfaced with various developments boards (such as an Arduino® compatible board). Features extremely accurate RTC chip with built-in 32 kHz crystal temperature sensor alarm clock capability Specifications supply voltage: 3,3 - 5 V DC RTC IC: DS3231 RTC accuracy: ± 2 ppm (from 0 °C to + 40 °C) temperature sensor accuracy: ± 3 °C max. I²C bus frequency: 400 kHz dimensions (W x L x H): 43,2 x 22,4 x 14,7 mm backup battery: CR2032 (included)