I have been a carpenter for many years and have used many different drill bits. Spade bits are needed for drilling holes for pipes, cables, etc. They're usually cheap and don't last long. In other words, they are disposable. And they don't like knots or nails found in the rivets during refinishing. These bits can cut knots and nails like butter. They cost a little more than a shovel, but they're worth it if you need to poke a few holes and don't want to go halfway to the hardware store.