This item is an ATMEGA328 microcontroller (328-PU or 328P-PU as available) in 28-pin DIP package. This is the type of chip used in my ARPIE kit, and is offered for sale to enable a simple self-upgrade path for ARPIE owners who do not own programmer hardware or are not comfortable using it.
The chip is programmed with the ARPIE 6 firmware, which was released in September 2019. Please see the ARPIE product page for more information. It also has an Arduino Duemilanove bootloader programmed on it and can be further updated using a suitable USB-TLL programmer.
The upgrade is compatible with any of the ARPIE kits I have previously sold. It can also be used to replace a lost or damaged chip or build a DIY ARPIE from scratch.
When replacing the chip, be careful not to bend the legs and make sure you fit the chip the correct way around. Take basic anti-static precautions (e.g. touch a grounded metal surface prior to handling the chip). With reasonable care, anyone can change the chip.