Designed to prevent frozen or stuck bits from slowing down your woodworking projects, the Porter-Cable 42999 allows the collet and collet nut to be removed as one unified unit, helping to prevent lost bits. This handy tool offers two helpful functions: it can be used to replace lost collets or to convert 1/2-inch bits to 1/4-inch bits, so you can use them with your 3 1/4-HP Porter-Cable router. The 42999 is compatible with the following Porter Cable Routers: 690, 691, 692, 7518, 7519, 7529, 7537, 7538, and 7539.