The Base Flatness Tester from Wintersteiger is a trusty way to determine if your skis are level. Even brand new skis, fresh from the manufacturer may have experienced a certain degree of warping. Skis high on the edges will feel grabby and erratic. Base high skis will feel squirrelly and 'loosey-goosey' underfoot. Both base high and edge high skis will require professional ski tunes. Additionally, base high skis can be difficult to fix. Make sure you bring your Wintersteiger Flatness Tester True Bar with you when ski shopping, so you know what to expect. How to check the flatness of skis: Look for light under the True Bar in the middle or by the edges of the skis when you place it on the base in the tip, under the binding, and on the tail.