For good legibility, the thermometers have a 200-mm aluminium housing with anodised gold-tone finish. The measuring area is permanently diffused into the anodising layer. The glass insert is filled with a blue fluid; the scale is permanently baked onto the glass. The scale graduation is 1 °C. Indoor thermometers have a mounting eye at the top and can be fixed with a screw. Outdoor thermometers are supplied with a mounting bracket.