The case is made of high quality 0,8mm thick brass sheet.
The surface is mirror finish polished and lacquered.
Front glass is PMMA (Acrylic glass).
All 842 instruments are front loaded as the 852 instruments for easy access.
Thermometer: -20°C to +60°C. -4F to +140F.
Hygrometer: 0-100% relative humidity.
Temperature reading ±1ºC (10ºC to 30ºC). ±2ºC (-20ºC to 60ºC).
Hygrometer reading ±10%.