Product Details:

Use this handy CRL Suction Base Ring for drilling outlets whenever you use diamond coolant or silicon carbide grain. Made of a special rubber compound Dual Durometer rubber which is harder up top to retain its shape, and very soft on the bottom for the suction lip to create a vacuum. The first hole is drilled then plugged by the included two inch (51 millimeter) rubber plug to retain the coolant for the drilling of the second hole. A nice feature of this drill ring is it won't break the glass if dropped on it accidentally because of the material it is made from. Easy to use: just wet the base with coolant or glass cleaner and press onto the glass.
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.