Brass knuckles (which are often made of steel, not brass) are weapons used in hand-to-hand combat. Basically, brass knuckles are pieces of brass or other metal shaped to fit around the knuckles. A hit from someone wearing these is extremely painful, and sometimes fatal. In most countries, the possession, let alone the use of brass-knuckles (sometimes called "knucks" or "knuckle dusters") is illegal, as they are considered to be a 'cold weapon'.

Knives using brass knuckles as their handle were common during the World War II era. A knife such as this is known as a "trench knife."

In London they are known as Knuckle Dusters