P
pennywise
I have got a laser line it just when doing a large room with say 20 to 30 lights it's nice to have the referance lines on the ceilng so you can visualise the final positions. The laser line can only project one line at a time so you mark out all the positions for the lights then find that they hit a couple of joist you then have to set the laser up to move the lights across etc were as with a chalk referance line you just have to measure from the wrong position to the new much quicker especially if your working with someone else.