Adafruit PiRTC - PCF8523 Real Time Clock for Raspberry Pi

Key Features Perfect for data-logging, clock-building, time-stamping, timers and alarms, etc Equipped with PCF8523 RTC Works with any Raspberry Pi (or similar single board linux computer) including the Pi 1, Pi 2, Pi 3, Pi Zero, A+, B+, Pi 4, etc. Fully assembled & tested PCB plugs directly into your Pi's GPIO pins - No soldering required! Will keep time for 5 years or more This is a great battery-backed real time clock (RTC) that allows your Raspberry Pi project to keep track of time if the power is lost. Perfect for data-logging, clock-building, time-stamping, timers and alarms, etc. Equipped with PCF8523 RTC, it works great with the Raspberry Pi and has native kernel support.Item Specifics1 - RTC BoardSize: 21mm x 20mm x 12mmWeight: 2.2gCR1220 coin cell battery NOT includedNote: Not a high precision device. Could lose/gain 1-2 seconds per day.