SRKi Lightweight Crank Pulley weighs about 665 grams, or 1.46 lb, and is manufactured in Korea using aircraft-grade aluminum. Factory crank pulley weighs about 2.25 kg, or about 4.95 lb.
Pulleys are the same diameter as the factory pulleys with lower weights, resulting in less rotating mass and less power lost, and faster engine response in the case of the crank pulley.