The Nova System™ gives you a wide range of profiling options in a single router bit with replaceable carbide tips. The innovation is in the bit. The easily replaceable hard carbide blades gives a whole range of profile options in a single bit, as well as other vital advantages such as durability, versatility, safety, service-free and cost effectiveness. Body type A includes both concave and convex knife retainers and ball bearing guide. Replacement parts: knife retaining screws #67084.