Luminous Spirit Bubble Level, Metal Housing, Bulls Eye Bullseye Vial, Blue-S Product Highlights Luminious, Blue/Silver. A luminescent Level. Use in in any lighting condition- at any time of day or night. Allow bubble level to absorb light for a few hours and it will emit light when darker conditions prevail. Framed in Silver Metal Housing. Quick moving Blue liquid. Phosphorescence material allows the glow in the dark effect. Otherwise known as photoluminescence. Photoluminescence is the ability of some materials to emit light after exposure to light. Durable Metal Housing, Circular Spirit Level - Ideal for tripods too. Product Description Framed in metal housing with glass plate and measuring grid. Bigger size to ensure stable positioning and clear indication of any sloping. Diameter 60 mm Height 10mm