AC motors with mechanical features developed for a certain purpose or application are known as definitive-purpose motors. They run on alternating current and only require a small amount of power to get started. The 50 Hz motors are designed to work with 50 Hz equipment that meets European requirements. When the power to the motor is withdrawn, the brake motor brings the machine to a halt. With a moderate starting force, instant reverse motors give instant reversibility. Metalworking and woodworking equipment are powered by stationary power tool motors. AC motors with vector (inverter) inverters produce constant torque over a wide speed range. Brushless blowers have a high power-to-weight ratio for hand-held power tools, while vibrating motors improve material flow.