The CRL Brass Tube Drill Replacement Head is used in conjunction with a CRL Brass Tube Drill. By replacing only the head, the tube drill can be retained for use without having to buy a complete replacement drill. Important Notes: Always wear the proper safety gear including gloves and 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.