I've used them on several pine (softwood) projects. No damage, cut well enough. If you're using them on hardwood I suggest having a good drill bit. My drill is only 14.4 volts (will be replaced soon) and I was cutting hard wood with the drill and these bits were draining the battery TOO quickly. Very thin steel case from a discarded DVD player (no more than 1mm thick). The 3/8" drill bit I used made two holes and the third hole destroyed it. It also won't cut soft wood anymore. 4 stars because I knew these $12 bits would outlive soft woods would, but they won't work on harder materials.Every consumer should have reasonable expectations and base their purchases on expectations.Hard material, find a set of bits designed for the job.I've barely made 3 holes (for Luckily that's all I needed). For soft woods and plastics these bits are great value. Use them properly. The "pumping" keeps the temperature down and prevents the steel from warping.