As the owner of a plumbing and heating business, I am also the fixer of tools and the sharpener of blades, and it's up to me to make my equipment investments last. One of my most onerous duties is sharpening the Selfeed bits we use. I've gotten good at it, but it's a time-consuming chore. So it was with great optimism that I tested Milwaukee's SwitchBlade Selfeed bits with replaceable blades. I got the plumber's kit with four commonly used bit sizes and a handy snap-in extension (which I can no longer live without). Besides spare blades, the kit has four spare feed screws and their set screws, all contained in a durable "lunchbox" that is one of the few plastic tool cases I haven't tossed out for being oversized.