This levelling device is used for AquaClear power filter models 20, 30, 50, 70, 110, 150, 200, 300, 500. Comes in polybag with header. Used to lever the filter against the tank to make sure the water level in the filter is not at such an extreme angle as to cause spillage. Measures 2/3-inch length by 3-1/5-inch width by 5-1/2-inch height.