Suction Cup: This glass cutter has a fixed suction cup, which make it can firmly hold the glass, holds center while cutter head scribes the circle. Function: This is a glass ceramic tile cutter for cutting glass in a exact round circle, perfect for hobbyists and professional glass cutters. Cutting Range: High hardness alloy cutter wheel for easy cutting, cutting range is a circular hole with a diameter of 13.5-40cm/5.3-15.75". Easy to Use: This glass cutter with oil tank, it can be automatically filled with oil, making it easier to use. Clear-cut Scale: The calibrated scale can help you accurately adjust the size of the cut hole, make your work more easy.