End Mills are a uniquely designed tool engineered for machining many materials such as aluminum, acrylic, plastic, wood, sign foam and MDF. The special end tooth configuration allows very aggressive drill-type penetration when a cut is being started. The flute geometry gives a much smoother "cut" and surface finish while allowing much faster chip evacuation when milling a groove. These interchangeable inserts fit the GravaDrill models GD250R and GD250K.