From Team Fortress Wiki
The Steel-Toed Stompers are a miscellaneous item for the Heavy. They appear as a pair of steel-toed platform boots with large bolts through the ankles.
This item can only be worn around Halloween or during a Full Moon; at other times of the year, it does not appear in gameplay, unless the server has Halloween mode enabled. However, it can be equipped at any time and can still be viewed on the loadout screen even when it is not visible during games.
October 27, 2011 Patch (Very Scary Halloween Special)
- The Steel-Toed Stompers were added to the game.