Description of DiamondSure Diamond Granite Ceramic Porcelain Cutting Tools: Premier Industrial Drill Bits
Bonded Diamond Grit: Electroplate bonded diamonds for optimum diamond life. Nickel Plated: Reduces bit friction and heat build-up and inhibits rust. Grooved Tip Edge: Provides maximum surface area & increases water "churn" for tip lubrication. Tip Lubrication Hole: Provides optimum tip lubrication by allowing water flow in and out of bit. Core Extraction Hole: Special holes in back of the "Bell" allow easy removal of cores or plugs.
They work really well, keeping the RPMs low and the drill bit cool. I used a water spray bottle and just kept spraying while I drilled. I would recommend it to a friend.
These drills are great but the centers are notoriously hollow and I don't know why. A pilot hole must also be drilled before using the drill. When you drill porcelain, you don't have to drill twice. This is the only downside, but the bits are killer.
DO NOT BUY! I installed a new Toto toilet in our master bathroom and had to drill 6 holes in the porcelain stoneware. I started with the Milwaukee Diamond Plus hole saw. After 5 holes I thought maybe it's worn out. So I switched the Diamond Sure drill to a diamond drill. This was enough for exactly 1/2 the hole until all the diamond dust came off the tip. half hole! I filled the holes with a Milwaukee drill bit. Jeff Bezos should be ashamed to keep this piece of junk.