Compact Line & Dot Lasers
There are a lot of inexpensive small line and dot laser on the market some being no more than toys. RedBack Lasers compact Line and Dot Lasers are built for the trade and can be re-calibrated if required, unlike some.
Two models the DL3 with horizontal and vertical lines plus ceiling cross and plumb dot down. The DLD5x has horizontal and vertical lines but also 5 laser dots for plumb level and square. Both come with magnetic base that also allows mounting on tripods.
Both come with an automatic two year warranty from RedBack lasers.