Which colour for which surface (cross-line laser)?

Red (650 nm): standard choice, lowest cost, sufficient in moderately lit environments. Light red (635 nm): noticeably brighter than 650 nm red at the same power, good visibility on most surfaces. Green (520 nm): appears roughly 5–7× brighter than red – the choice for very bright environments, visible in daylight, large distances or dark surfaces. Blue (450 nm): ideal on wood, vegetation, greenish or yellow surfaces – where red and green get lost in the background. Light blue (488 nm): high contrast on warm-light spectra, a special colour for surfaces such as red-toned woods.