Achievement weapon icon TF2
"I don't know who to thank first... oh, I know, me!"
The Scout earning an achievement item

Achievement items are unique items, weapons, misc, action items and hats, that can be obtained via the completion of achievements in Team Fortress 2. Each individual class has 3 Milestone achievements. Completing each Milestone will grant the player a specific weapon for that class. Other achievements award items to players for completing other tasks, such as defeating bosses. Items earned via achievements can not be traded.