Collar works as a restrictor, and changing the shape will change significantly how the lever operate. For so long the shape of the restrictor haven't change too much. We are already familiar with the circular, octagonal, and square shape, they are works great for different playstyle.

Most Fighting Games executions are focused on the lower half area (down, forward, and back) for "up" direction only use for jumping, side stepping, and normal moves. It is because Fighting Games was designed for Arcade Stick controller, and inputting upper directions is harder compared to lower direction.
So we have an idea to make the restrictor for "up" direction shorter, make it easier and faster to inputs. Depends on the shaft size, the reduced throw distance is about 20% (for 7mm shaft) up to 50% (for 12mm shaft). Fortunately on Golden Lever every switch can be adjusted to have different spacing, and for this purpose we can adjust the "up" switch closer to compensate the shorter throw, especially when using Big Shaft.

We decide to use square shape for the upper half because it have corners and can help the user to input diagonals precisely, this is important since inputting upper diagonals is much harder compare to lower diagonals. In 2D Fighting Games, diagonal jumping is very important and this mod can help a lot.

We have 5 new combination that you can use on Golden Lever:

1. Circular-Square GL collar, it have normal circular shape on lower half and short square on upper half.
   
2. Octagonal-Square GL collar, it have normal octagonal shape on lower half and short square on upper half.
   
3. Short-Square GL collar, it have normal square shape on lower half and short square on upper half. for this model, you can rotate the short side to any sides you want (Down/Left/Right).
   
4. Octagonal-Circular-Square GL collar, it have circular shape on lower half with sharp corners from Octagonal shape, and short square on upper half. Sharp corners are easier for user to feels the diagonals.
   
5. Circular-Octagonal-Square GL collar, it have circular shape on lower half with radiused corners from Octagonal shape, and short square on upper half. Radiused corners are more smooth compare to OCS, it almost feels like circular but users still can feel the diagonals.
   

Mr. Nest make the detailed data sheet about this new collar, you can download it from this link