TIMCO Arrow Head Tile & Glass Drill Bit - 8 x 80mm

OK

Bought 2 x 6mm and 2 x 8mm, just in case. The 6mm drill tips were off centre and the first broke. With extra care, the second cut the two holes required in very, very hard porcelain floor tiles. The 8mm drills were properly concentric and the first was blunt after two holes. The second drilled the remaining two 8mm holes required. So, they did the job of drilling 6 holes in hard porcelain tiles but all 4 drills are now used up and blunt. But they did what I bought them for.