These certified thermometers are manufactured using a type N 16 soda lime glass with diameter ~6 to 7 mm.

• Graduation lines are fine and easily readable
• The colour of the glass is standardised in yellow giving a better reading than the white back
• MRA traceable thermometers

The graduation is printed and fused in the glass with a special process and so the graduation resists to all chemical products except fluoridric acid and hot soda (to a lesser extent) because these two attack the glass. They are calibrated for total immersion.

They possess a suspension ring and an expansion chamber to support temperatures higher than those of the thermometer.