This package carries (a)-(b):

(a) 1 Piece of B10 (3/8" / 10mm) for 10mm / 3/8 Inch high / thick granite marble concrete quartz glass countertop / vanit top edge bullnosing Diamond Brazed Router Bit to do Demi / Half / Roundover shape bullnose.

The inner hole of this router bit is 7/8" to 5/8".

it works with grinder or  polisher with 5/8"-11 Thread spindle.

Important Remind: Please make sure that your grinder or polisher speed is below 5000 RPM when using with it.

(b) One Lock Ring Nuts and wrench set (the pairs of lock ring nut is necessory to attach the router bit to your 5/8"-11 thread spindle grinder / polisher).