Most corners are 90° which is why most corner guards are
90°. But there are are walls of other angles and the most common are 135° and 45°.
Corners that are 45° especially need protection given that there is less material on the corner due to its small angle. While company makes a 45 degree corner guard our adjustable angle corner guard was designed for the this purpose.
The additional benefit of using a corner guard with an adjustable angle is that it is able to conform to the wall even if there are slight variations in the angle (e.g. 43 degrees or 47 degrees) due to the construction or movement of the building over time.