Küchenprofi: Roast Thermometer This roast thermometer comes from Küchenprofi. To use it, simply insert the pin of the thermometer into the roast until the point reached the centre of the roast. When the thermometer reaches the desired temperature, the roast is ready. The diameter of the scale is 5.5cm/2.2in and the overall length is 12cm/4.7in with the probe length being 10.5cm/4.1cm. The temperature scale is 0°C - 120°.