For ideal stock support, it’s recommended that the router bit opening be approximately 1/8″ to -1/4″ larger than the bit diameter This clearance is enough to allow for air flow as well as stock support while routing Includes a blank ring which can be drilled or routed for a custom size Set includes: solid, 3/4-inch, 7/8-inch, 1-3/8-inch, 1-5/8-inch, 1-7/8-inch, 2-1/8-inch, and 2-3/8-inch Custom made holder included