The quick fit bit system is unlike any other bit in stained glass It is designed to be quick to change without the use of a hex wrench or other tools like conventional grinder bits. With a flip action of the holder's lever, you can change your bit, or the grit of the bit, in seconds There's no need to find and use keys or locking tools - no grinder freeze-ups. This is the Rapid Grind (Coarse Grit) replacement diamond bit sleeve for the Quick Fit Bit System. Note that this is the diamond bit sleeve only. Holder sold separately.