Hole saws may not be the sort of tool you use often, but when the need arises – as it almost inevitably will – having the right size can really save the day. With all the standard sizes* typically used for plumbing, wiring, doorknobs, and even ductwork up to 4" in diameter, this seven-piece set is an excellent price for carbide-tipped tools, which stay sharp much longer than common bimetal hole saws.