The 3 different sizes of cone mandrels fit into the base of the tool for easy storage. This set includes a 5mm x 2mm, 8mm x 2mm and 12mm x2mm mandrel.To use, simply insert your desired mandrel into the base and tighten into place with the included Allen wrench. Place your wire into the insertion hole in the mandrel, hold it in place with your thumb, then gently twist the mandrel until the wire spiral reaches the top. The mandrels can also be used with the Professional Coiling Gizmo Chuck. Use the tool with a bench vise by inserting the base into the vise. Spiral a coil around a large gauge wire for an incredibly beautiful custom cone.