WGS Short Run 2-1/2" Diameter Diamond Plated Drill Bit. These professional quality drills provide an economical alternative when the higher yields of our standard bits are not required. The heavy layer of diamond coating enables yields of up to 100 holes when used properly. These diamond coated drill bits feature knock-out holes in the body for easy spent plug removal. All diamond bits must always be used with suitable diamond coolant applied by spraying or immersing the bit while drilling. For drilling glass, tile and stone. Hole Diameter: 2-1/2", Shank Diameter: 3/8", Overall Length: 2-1/2".