From the designer, Milwaukee Dave:

This is my design for the M12 2nd Gen Fuel drill and impactor, this design allows for the drill and the impact to have the M12 6Ah or high output batteries, I did try various ways to get these drills in with different batteries, but in the end i went with this design as this is how i use my drill and impact I always have the 6Ah battery in not the smaller one, the design allows for the screwdriver bit to be left in the impact and small storage around the chuck, the design also allows for the impactor to have the bit holder on the side, as with my new inserts for the drawers this design allows for fitting on left or right with the same print.

This insert takes up half a drawer and is designed to fit in:

3 Drawer Packout: 4822-8443

2 Drawer Packout: 4822-8442

Multi Depth 3 Drawer Packout (Bottom Drawer Only): 4822-8447

Drill Model Number: 3403-20

Impact Driver Model Number: 3453-20