Round Head Keys:- Round keys are generally used for Automobiles, gearboxes, starters, alternators, fuel injection pumps, oil pumps, water pumps and brake compressors, Two wheelers, Electric motors, alternators and switch gears, Machine tools and all types of pumps Textile machineries, Pharmaceutical Machinery, Heavy Duty Machinery, Earthmoving Machinery, Automotive Cran etc. 

In mechanical engineering, a key is a machine element used to connect a rotating machine element to a shaft. The key prevents relative rotation between the two parts and enables torque transmission.A key is used for temporary fastening. For a key to function, the shaft and rotating machine element must have a keyway, also known as a key seat, which is a slot or pocket the key fits in. The whole system is called a keyed joint. A keyed joint still allows relative axial movement between the parts.