A bundle of our most popular bits, this 3-pack of 1 Up cut, 1 Down cut, and 1 Compression router bit provides a great starter set of bits for your most common cutting needs, at a nearly 15% savings versus buying individually. All three bits are solid carbide, with a 1/4in diameter shank and overall length of 2 1/2in. All of which are perfect for the Maslow CNC and other CNC machines. - Downcut Spiral Bits are best used for thinner materials, or when a high-quality cut finish is required on the top surface of cut parts. The trade-off for this cleaner cut is that waste material (sawdust, etc) is pushed down into the machine bed rather than being lifted out, the way it is with an upcut spiral. - Upcut Spiral Bits pull chips (and your material) up and away from the table (with upcut, the airplane propeller spins the correct direction). They are great at clearing out chips from your cuts to avoid overheating your bits and therefore excel at making deeper cuts - Compression Bits are a combination of up- and downcut bits, which you can see in the complex fluting of the bit. These specialized bits simultaneously pull out chips and debris, while leaving a clean cut surface on both sides of your work material. In this sense, they carry the best of both worlds. Compression bits are great for melamine and projects were both sides of the cut material need a clean finish. The trade-off of compression bits is in their higher cost. It is therefore recommended that these bits be reserved for the specialty projects they are intended for.