The Parf system relies on the fine tolerance of the fit between the dog holes and the dogs, neither too tight or too loose. Changes in humidity can cause difficulties in inserting or removing Parf dogs. This stainless steel UJK Combined Chamfer and Reamer tool does two jobs at once. It has a 10mm hexagonal shank for a secure grip in a cordless drill chuck (use slow speed). The Reamer portion has a gentle lead in and four cutting flutes to ream the holes to a precise size. Your Parf dogs will fit snugly without wobble yet still enable you to remove them without difficulty. After the Reamer the Chamfer comes into action, cutting a neat, shallow chamfer around the top of the dog hole. This chamfer allows full use of UJK super dog and anchor dogs etc. In addition, by removing the sharp edge around the hole, it prevents damage from repeated insertion of dogs, clamps and other accessories. The Chamfer features a solid tungsten carbide cutter. Note: the Chamfer works best in MDF, HDF or ply with a melamine facing. Unfaced plywood may experience some slight tearout.-bg