Glaesel Self-Adjusting Bass Bridge with Wheels 3/4 Size Self-Adjusting Bass Bridge with Wheels 3/4 Size The Glaesel Adjustable Bass Bridge with wheels features moveable feet which conform automatically to changes in the top curvature, achieving a precise fit without carving the feet The wheels adjust the height of the bridge and string action This is handy in places that experience extremes in temperature and humidity The Glaesel Adjustable Bass Bridge with wheels features moveable feet which conform automatically to changes in the top curvature, achieving a precise fit without carving the feet