One Piece Construction Gives Rigidity and Durability The "Old Reliable" Way to Drill Glass This CRL Steel Tube Drill was designed for use in our CRL Tripod Drill or similar type drill machine. It works with an abrasive grain such as CRL Silicon Carbide Grain to "drill" holes in glass through rotational abrasion. A coolant (or water) is mixed with the abrasive to form a slurry which is retained by a CRL Rubber Base Drilling Ring . The even and steady rotation of the tube drill against the glass will produce a clean hole with minimal breakage or chipping. This CRL Steel Tube Drill is the economical fulfillment of your glass drilling needs. The all-steel welded drill measures four inches (102 millimeters) long and it can be used down to the second set of abrasive grabbing slots. It has a 1/4 inch (6.35 millimeter) diameter shank to fit most machines. Always wear the proper safety gear including eye protection when drilling glass. Work should be performed on a flat, horizontal surface. A Ground Fault Circuit Interrupter must be used when using any type of electric tool in conjunction with water or coolant. Failure to follow any of these precautions can result in operator injury.