$53.99 Neiko Pro 10238B SIlver and Deming Industrial Drill Bit 1/2-Inch Shank with 1-Inch Diameter 
Eagle 1/2 inch 24 in Flexible Cable Installer Masonry Tool Attachment Drill Bit | eBay
Amazon.com: 1/2 X 24 Masonry Drill Bit: Industrial & Scientific
