Developed and designed entirely by CeramicSpeed, the Oversized Pulley Wheel System (OSPW) for Shimano 9000/6700 offers the ultimate drivetrain optimization for your bike. This OSPW system features a pair of 17-tooth aluminum pulley wheels, available in red and black, housed in a specially designed polyamide (PA) and carbon cage. The oversized 17-tooth aluminum pulley wheels, upper and lower, are mounted with standard or coated CeramicSpeed bearings. The Oversized Pulley Wheel System (OSPW) is the product of choice for many of the world's top cycling and triathlon teams. This specific system is compatible with Ultegra 6700/6770/6800/6870 mechanical and Di2 rear derailleurs and with Dura Ace 7900/7970/9000/9070 mechanical and Di2 rear derailleurs. The system is compatible with up to a 28-tooth cassette on most bikes, depending on the derailleur hanger. In the package: Complete OSPW for Shimano 9000/6800 system CeramicSpeed UFO TECH Bearing Oil 15 ml dropper bottle for pulley wheels.