The concentricity and taper angles are precisely controlled which allows perfect locking and concentric movement to the tool held. These are available in two types:
A Grade - (Hardened and Ground)
Manufactured from case-hardened Hi-Tensile steel (20 MnCr5/SAE8620), these are fully hardened and are ground on the inside and outside
Workshop Grade
Manufactured from carbon steel, these are ground on the outside and have a reamed finish on the inside
Permanent marking of size on the tang ensures convenience in use