CRL revolutionizes onsite drilling with tomorrow's technology. The all new Port-O-Holer Glass Drilling Tool drills holes up to two inches (50.8 millimeter) in diameter in glass and mirror, regardless of the location. All you need is your own cordless or 110V power drill w/GFCI, and you are ready to drill. Never has there been a tool that is so simple and economical, yet so accurate and easy to use.