Operation Gear Grinder Badge
The Operation Gear Grinder Badge is a Miscellaneous item wearable by all classes. It is earned by completing your first mission of the "Operation Gear Grinder" Tour of Duty in Mann Up mode. It tracks a player's progress through the various Mann vs. Machine missions. The badge's level will increase based on the amount of times you've completed the challenges in Mann Up mode (level 100 requires completion of 594 missions).