Had a look at them, thought it said they were only good for a few holes, better off getting some decent ones that will last and charge accordingly for the holes that you have to drill, charge about a fiver per hole for up to 40mm
When punters ask if we have a cutting service I reply "you're looking at him" We recently were allocated a diamond core water cooled system jobby.WKD they p*ss through porcelain. Various sizes from 8mm to waste pipe size,and an adjustable suction cup device that hooks up to a primer bottle.Sell like 'ot cakes Gaz