Disagree with just about everyone.
HD and Lowes do not sell the right kinda laser.nor do 90% of laser companies.
What you need is a laser that shoots 2 LINES (not dots like most of them do ) at a 45 degree angle.
Don't waste your money on anything else. These things will make laying out rooms a breeze...no more 6-8-10
a straight laser will not be any better then a 5 dollar chaulkine and you will indeed have a hard time seeing it.And it will be 1/2 wide after 40 feet.
A rotory does not give you 45's and has limited use and longer set-up time.
There are two I would reccomend one is 400.00 the other 800.00. they have the same size lasers. I use the cheaper one but never tried the more expensive one yet but the more expensive one can do the extra horizontal line(follow the link).
The cheaper one is an advantage also as it comes with a angle finding plate.
heres the links:
Remember these are LINES not tiny useless dots that take a PhD is physics to figure out.
Also remember they shoot at a true 45 degree and most all others can't do this feature. This is the most useful feature a laser can do for you, don't think of buying one that can't do this..makes set up really easy.
the expensive one, introducing the SL-24
http://www.contractorstools.com/lasersquare_sl24.html
the one I use:
it's called the Accusquare
http://www.contractorstools.com/leve...pecsacsqr.html