1. It is made of high quality heat treated alloy steel for maximum strength. 2. 3-roller cones and 4-roller cones available. The body of Hole Opener is made of high quality heat treated alloy steel for maximum strength. Cutter arms, equipped with removable cutter, are hard-faced and welded on body. The hole openers have three or six jet tubes with replaceable nozzles, so that jet streams quickly ...