Adding this Strange Part to a Strange-quality weapon will enable it to track an additional new statistic!
This is a limited use item. Uses: 1
Only found in crates, Strange Parts will help you study specific aspects of (what I charitably call) your performance in battle by letting you customize your favorite Strange weapon. Now you're free to track the number of enemies you gib, projectiles you reflect, heads you've shot, and more.
— The Administrator
Strange Parts are exclusive tools that are only obtainable via crates, with the exception of the Full Moon Kills, Halloween Kills, and Robots Destroyed During Halloween parts which can be found as a random drop. Strange Parts can only be used on Strange weapons. They allow players to track additional statistics such as number of headshot kills or buildings destroyed.
Up to three Strange Parts can be applied onto one Strange weapon. Certain Strange Parts cannot be used on certain weapons; for example, the Headshot tool cannot be used on a Strange Wrench. When applied, it will not count any previous stats. Strange Parts can be individually removed from a weapon using the Restore button in the backpack, allowing the player to remove a strange part of their choosing; however, a part which has been removed will not be returned to the player, and instead will be permanently lost.
Certain parts are only compatible with certain weapons. A table of the restrictions is given below.
These restrictions are based on specific attributes listed in the items_game.txt file, which do not necessarily reflect weapon functionality. The tables below and elsewhere in the wiki are based on these attributes.
There are some mismatches between weapon capabilities and strange part compatibility which are not bugs, strictly speaking. E.g. the Medi Gun can be used to extinguish team-mates, but it isn't possible to apply the Allies Extinguished strange part to a strange Medi Gun. In this case, it's probably because the Medi Gun takes a few seconds to extinguish burning teammates, but all the weapons that are compatible with the Allies Extinguished strange part work instantly; only the latter mechanism is tracked by the strange part.
The Strange Part: Underwater Kills can be applied to any form of strange flamethrower, despite the fact that enemies are immediately extinguished when they enter water, along with that flamethrowers cannot be used in a body of water.
Servers using an altered tf_playergib setting will not change the way the Gib Kills counter is counted, only kills that would normally gib will still be counted.
All the strange Flamethrowers do not count issues with reflected projectiles. That means they do not count gib kills with deflected rocket/grenade, headshots with deflected arrows and kills while explosive jumping on deflected enemy explosives. As a result respective Strange Parts can not be applied.
Destroying Sappers with any Strange Engineer wrenches will not increase a buildings destroyed counter, however destroying Sappers with a Strange Homewrecker or a Strange Neon Annihilator will increase a buildings destroyed counter.
Strange Part: Allied Healing Done will not count overheal points.