Trap Flex

Trap Flex is the Quirk used by Habit Headgear.

Description
Trap Flex allows the user to flex their trapezius muscle to extreme degrees, allowing them to cover their whole head with their shoulders. The flexing gives them a fair amount of speed and strength.

Weaknesses
While Trap Flex does provide extreme speed and strength, it is nowhere near as strong as other strength-based Quirks, such as One For All, as All Might was able to knock Habit out with a single blow to the back of the head.

Trivia

 * Trap Flex is also referred to as Oversized Trapezius in My Hero Academia: The Strongest Hero's combat archive.