Radiators actually only radiate 20% of the heat they produce, the remaining 80% is convected up to the ceiling or escapes through a nearby window. Radiator fans are innovative gadgets that redirect that 80% and blow it out into the room. The Radiator Booster does this with one fan out of the side of the radiator and the Radfan uses between two and six fans to blow the heat out into the room, to give warmth where you want it.
This really works. Unobtrusive slight noise from the fans. We have a thermometer in our room so I can tell you really does make it warmer quicker. If the fans were any stronger it would cause drafts as is just set it and forget it.