8th iteration or HW108 actually means this is the eighth revision of the A3 being produced. It all started with HW100 back in 2016. Each new version brought important updates part of the normal product lifecycle. The latest one answers a tough question on the maintenance effort (both hardware and software).
As you know, the A3 comes in multiple varieties, with the same sensors but different connectivity options. It supports Ethernet, Wifi, LoRaWAN or GSM. It was becoming increasingly difficult to maintain the hardware changes across the several flavours. The model INDUSTRIAL was the first to introduce a solution, in version HW105, with a modular design that uses a generic motherboard and add-on connectivity modules. So you can have something like lego pieces to customise the final result: the motherboard with sensors and the core functionality, and a second PCB that handles the connectivity. This worked great, so the same principle was introduced to the A3:
The add-on boards are inter-device compatible and offer a great deal of flexibility. Other than that, the A3 still monitors a plenitude of parameters, including temperature, pressure, humidity, volatile organic compounds, carbon dioxide, formaldehyde, ozone, noise, particulate matter pm1, pm2.5 and pm10. See A3’s full specs here.