Stanley Intelli Tools INT177340 Cubix Self Levelling Cross Line Laser £34.95 Delivery at no additional cost for Prime Members You Save: £39.20 (53%)

Screwfix it's £41.66

These are pretty good, reasonably accurate and give a usable beam of up to about 3 to 4metres across. The beam isn't mega bright but usually fine in regular lighting.... however I sometimes turn off the room lights to see a wide beam range, mark the wall then lights back on. Ideal for lining pictures on a wall, tiling, shelves etc. It's not micro accurate as the beam is about 1.5mm thick and gets a bit thicker at the edges of the beam but if you're trying to align things across a wide area where a traditional spirit level won't reach then this is ideal.

Plus it looks cool, like a yellow robot thing from that 1980's kids cartoon.