Brass knuckles

These weapons fit snugly around the knuckles and allow you to deal lethal damage with an unarmed strike. You may hold, but not wield, a weapon or other object in a hand wearing brass knuckles. You may cast a spell with a somatic component while wearing brass knuckles if you make a successful concentration check (DC 10 + the level of the spell you’re casting). Monks are proficient with brass knuckles. Brass knuckles can’t be disarmed.