The Bosch DIY Quigo Laser (0603663101) is an ingenious little cross line laser which can be fixed anywhere using the clamp that comes with it (1 - 6cm). It is super easy to use and self levelling so it is always 100% straight. It features simultaneous projection of a horizontal and vertical laser line with ± 8 mm/m accuracy.
Super easy to use
Self levelling - always 100% straight
Horizontal & vertical laser
Fix anywhere with clamp