Ball end hex keys are especially for cap head and grub screws that are difficult to access. The long arm ends in an accurately ground ball end enabling use at an angle of up to 25° from vertical. The short arm is ground and chamfered ensuring a perfect fit in the screw head; the long arm adds a little extra torque when loosening stubborn screws. Ball end, long arm hex keys are one of the most useful types. These are special alloy steel, hardened and heat treated for high tenacity and wear resistance. The bronze finish helps to resist corrosion.