Gila drilling guide kit includes one suction base and four drill guide rings in an aluminum carry box. The four size guide rings are 1", 1-1/4", 1-3/8" and 1-1/2". The drill guide ring will keeps the core bit in correct position and prevents the core bit jumping or skipping on your work piece. The most cost effective way to produces clean and accurate holes with ease every time on any granite, marble or tiles.