The NORAM 1600 Series provides noload starting, overload protection, speed control and the electric motors to reach starting torque requirements. Featuring 360° of shoe contact surface, 1600 Series clutches have been designed for more horsepower. Specifications Rated for 6 to 10 horspower engine 1" bore 1/4" keyway Bearing; ball Single Pulley with 4" OD for A or B Belt Engagement Speed = 1800 rpm