The NixieCron M4 offers a high-precision watch chip, temperature compensated with a deviation of only a few seconds per month. It comes with a sound module, that plays hour gong and announces the current time at the push of a button. You can also connect it with the DS18B20 temperature sensor and configure it via a rotary knob.
Changes, updates, extensions are easily possible via the LED-Basic development environment.
Click here to download the software necessary for any modifications you want to perform.