The PLL 2 is a cross line laser with an integrated digital display which shows the angle of the laser line being projected. The cross line laser is perfect for aligning pictures shelves light fixtures etc. on a wall. The incline function allows you to do this perfectly level or at a predefined incline/slope. This means you can have wallpaper tiles patterns etc. at any desired angle. The incline function not only makes the PLL 2 perfect for projecting a laser line at a predefined angle but it can also be used as a spirit level as the incline is displayed on the digital display. The on/off switch makes it simple to use you simply switch it on to either locked mode (for the incline function) or unlocked mode (for a self-levelling laser line) and select a cross or individual laser line using the mode button on top.