It specifically fits the Milwaukee 48228435 PACKOUT Compact Organiser.
The specific M12 Stubby Impact (3/8) that this is designed for is model 2554-20, link provided here: https://www.milwaukeetool.com/Products/2554-20

And the specific Socket set it accommodates is the "43PC SHOCKWAVE Impact Duty™ 3/8" Drive SAE & Metric Deep 6 Point Socket Set." Link here: https://www.milwaukeetool.com/Products/49-66-7009

Features - Super Flexible Design

Multi Layered Storage - Zero wasted space, Jonah designed an entire custom storage area under the Standard sockets. The Standard Sockets all sit in a custom tray that you can lift out to access the space below. This huge storage space is perfect for your extensions and other extra kit and runs the full length of the Packout!
Rubber Boot Support - Two dedicated options to pick from:
- Standard - Custom sized for those not using the protective boot.
- Rubber Boot - Custom designed with a larger opening to accommodate the use of the rubber boot. This print is physically labelled with "Boot" inside the insert. You can store the tool without the boot in this insert as well, it may just move around a little as it has extra space meant for the boot.
Secure Sockets - Designed so the sockets sit right near the underside of the lid. You could flip the box upside down and the sockets will remain in their slots!
Labels - Comprehensive labels are included for your sockets. Labels indicating size are in the bottom of every socket slot AND included on top.
Battery Compatibility - Designed to accommodate as many battery configurations as possible. It will support the following: Standard 2.0Ah, High Output 2.5Ah, Standard 4.0Ah, High Output 5.0Ah or no battery.
Belt Hook - You can store your tool with the belt hook installed on either side, I've designed the insert to accommodate both in the single design.
Tray Lifting Handles - Jonah incorporated two options to help with lifting out the tray that holds the Standard Sockets.
- Access Holes - Finger holes are included under the 19mm and 3/4" sockets. Simply lift out one or both of those and you'll be able to use your finger to lift the tray out.
- Side Handle - If you have your tool out of the insert, there is a recessed area near where the belt hook would usually be. This gives an easy grip to lift it up and out.