The kit is based on an Attiny404 microcontroller programmed in Arduino. On the back is a CR2032 battery, which makes the kit portable. There is also a key chain holder. The soldering process is simple enough based on the mark on the PCB. Included in delivery https://elecena.pl/product/25933537/333138-soldering-kit-stop-me-attiny404 2024-05-24 https://elecena.pl/product/25933537/333138-soldering-kit-stop-me-attiny404 2025-04-03 https://elecena.pl/product/25933537/333138-soldering-kit-stop-me-attiny404 2026-02-21 https://elecena.pl/product/25933537/333138-soldering-kit-stop-me-attiny404 2026-06-28