From the designer:

This is a custom insert that I have designed to fit your Milwaukee Packout to better store your long series drill bits and reduced shank drill bits! It specifically fits the Milwaukee 48228436 PACKOUT Low-Profile Compact Organiser.

I have designed it so that the drill bit holders are fully removable from the insert allowing you to customise your set up. You can use both or just one. If you would like to see the sizes of the drill bits supported, I have attached images in this listing with dimensions.

Also, this is the specific reduced shank drill bit set that I have for context on further details:
https://sydneytools.com.au/product/xtorque-xt8red-8-piece-metric-hss-reduced-shank-drill-set

We now offer labels to identify which tools are in which case.  Labels are offered at a discount when purchased with the matching insert, and are offered in black or gray.  Please see pictures below for color reference, but the labels which corresponds to this insert will say DRILL BITS on them.