They fit well and work as expected. Problems arise when using a Dremel as a router. Sometimes the beats will kick in, but usually if you take your time, don't mess up your work and kick it off your desk. If you use a real router, the bits are MUCH cheaper and work MUCH better. These bits are not carbide and will depreciate in value. Kinda cool for five bits. I got about 20 for $20 at a Lowe's sale and a few months later I got a 150 from Blue Hawk for the same price. My recommendation? Be patient, look for in-store sales or returns in decent condition, and you'll get lucky from time to time. Paying full price isn't necessarily the best option, but if you have the money and want the convenience, shoot. They work and do what they are supposed to, but are constrained by tools and materials.