With 7/8" Recess and Includes 10mm and 8mm Bolts. You may find more expensive bits but you will not find finer.Available in Position 1 and 2 Only.The Single breaker bit is a terrific addition to this semi 45 Degree profile for speed and bit longevity, use first to save shape on Position 1 Bit. Designed to operate on all routers up to 10,000 RPM. Optimal L bit speed- 7,000 RPM for L-20 & 6,500 for L- 30.CUSTOM PROFILES AVAILABLE UPON REQUEST