The Sram PG950 9 Speed Cassettehas been tested on the pro circuit and proven on the podium so you can rest assured you're investing in a quality product. With its heat treated steel and chrome plated sprockets this is an incredibly durable cassette with an impressive strength to weight ratio. What's more, this bike cassette benefits from Sram's superb PowerGlide II, a cassette technology which offers more reliable, incredibly durable, superior shifting performance with its optimal tooth profile and shift ramp design for speedy, positive index shifting.Sram PG950 9 Speed CassetteTechnology: PowerGlide IISpeeds: 9 SpeedRecommended Chain: PC-991, PC-971, PC-951Lock Ring Material: Heat Treated SteelSprocket Material: Chrome Plated