An impact resistant spirit level is made from red polystyrene plastic that withstands temperatures between –15°C and +60°C. Crush-proof block vials have very high transparency and durability. Horizontal vial have luminescent reflector and there's a V-groove in the bottom to allow use on pipes. The radius of the vial is 200 mm, giving a sensitivity of 10 mm/m. Tolerance in normal position is ±1.0 mm/m. The liquid in the vial is a coloured oil mixture whose low viscosity gives the bubble optimal freedom of movement. It has highly resistant to ultraviolet light and temperature fluctuations and the anti-static properties of the liquid means that the bubble is not affected by static electricity.