Designed for 1/2 and 5/8 inch thick glass and acrylic, most glass tanks from 110 to 200 Gal. & most large acrylic tanks up to 48 inch long and 30 inch high. The inside magnet projects 1/2 inch beyond the outer magnet. This extended reach allows cleaning beyond the visible edge of trims and canopies. Other advanced features such as ergonomic grip, replaceable pads for glass and acrylic, large 2.5 x 3.75 inch cleaning surface and one year warranty set this product apart from all others. A definite best buy!