RaceFace Turbine Chainrings (Black, 104-mm 38T 9 or 10 Speed) New asymmetrical tooth profiling and more upshift and downshift zones yield instantaneous smooth and quiet shifting, even under load Three times stiffer than the previous Team chainrings without any weight gain-net result is much sharper, quicker and more responsive shifts as well as increased resistance to impacts Machined in Canada with US made aluminum