Thicker Locking Ring
This is a thicker locking snap ring to make up for a bit too much play in the original (for my printer). It is designed to more closely match the contour of the slot, so it is also directional (decorative slot faces out). This allowed me to clamp parts with much more force while the original would release the jaws due to deflection at this snap ring.
Thanks to the original designer of the chuck, it's a very cool piece!