Like all other Peanut stoves, the Bignut is made of cast-iron and has the amazing capability of easily igniting full-size logs even after a fire has almost gone out. Just a few small embers left at the base of the stove is enough for the Peanut's flamethrower style primary air system. More info here.
The wonderfully named "Bignut" is a larger version of the standard-sized Peanut 5 and the biggest seller of the range. The canny amongst you may have noticed that the Bignut is the same size as the Peanut 8 - fatter firebricks inside allow the stove to be sold as a "nominal 5kW", thus avoiding, in most properties, the need for an air vent in the room.
The Bignut has an impressive 80.1% efficiency rating and is, as the name suggests, big.