Brightness:
The light output of any Betalight is governed by two main factors, the first being the final colour of the light emitted by the Betalight; the second being the total volume and pressure of the gas that is trapped inside the glass tubule. This essentially means that a lower volume of gas at maximum pressure will never be as bright as a larger volume of gas at the same (maximum) pressure.
Each individual ‘colour’ is created by blending different Phosphorous compounds into the Tritium gas. Consequently, there is always variation between the light output of different colours; with the brightest colours always being green and blue, closely followed by the white. Red, purple and orange Betalights are the least powerful in terms of raw light emission.
* Also available - Small (10mm x 2.5mm) and ATTs (12mm x 2mm)