These systems enable the transfer of heated (or cooled air) from one room with (say) a wood fire to another part of the dwelling – usually bedrooms. These systems can be automated as required, but usually it is more efficient to manually control (by flick of switch) on an as-needed basis.
You can buy a cheap system elsewhere – but a quality system needs a quiet powerful fan and most importantly ducting that preserves hot/cold air from point A (the fireplace) to point B (wherever you want the heated/coooled air)