HiLetgo 0.56 Inch 4 Bit Red Digital Tube Electronic Clock DIY Kit Clock Electronic Production Suite Time Chip AT89C2051 FR-4 PCB for Students Science Electronics Learning Education A good exercise for students in electronic production With second correction for precision calibration Minute and second can be displayed independently Two-Way alarm clock setting (can turn it off ) Time accuracy: error range 1 second per 24 hours