Diamond core drill bit(core drill bit, drill bit, core bit): Drills perfect holes in block, brick, concrete and other Diamond core drill bit(core drill bit, drill bit, core bit):Drills perfect holes in block, brick, concrete and ... to 450mm, pls specify when ordering.Segment on the core bits can be crown or split segment (normal type, ... .5*8/10 14 Customized size and diamond grit available upon request