Do I need a green-beam laser measure or is a red beam fine?

It depends on where you work. Across specialist-community threads, the recurring point is that green beams are dramatically more visible in bright light and outdoors, with one r/Tools commenter noting red lasers are roughly five times less visible than green. For indoor work against walls a red-beam unit like the Bosch GLM100-23 is perfectly adequate and cheaper; for sunny exteriors or long runs, reviewers consistently steer buyers toward green beams or a camera-assisted model.