The major advantage of green laser technology over red laser light is superior visibility. It can be seen more clearly, especially when the general conditions are brighter. This comes down to a simple biological fact. The human eye is four times more sensitive to green light than it is to red light. In practice, that means a green reference line produced by a laser levelling device will be easier to see than a red reference line, especially on a sunny day either outdoors or where a lot of daylight is coming into a room. As a result, working with a red laser level can sometimes be challenging. A bolder reference line is clearly better when it comes to making fine judgements about the positioning of things.

One solution is to black out the windows when you are using a red laser light for levelling. But this is rather labour-intensive and not always practical. People may be coming and going around you and, of course, the site may be outdoors.

The more practical solution is to move over to using a green line laser level if possible. For example, the Bosch GCL 2-50 CG Professional combi laser would make the ideal laser level for small-area projects where accuracy is essential, but the light level cannot be reduced. Think of kitchen installation or joinery tasks carried out in a bright space.