The PowerTrac Elliptical™ (PTE) Wolf Tooth's patented design means a slightly less oval gear (10%) with less aggressive timing (112°) than competitive versions; any change in pedal travel is imperceptible to most riders, but still provides the POWER and TRACTION benefits inherent in oval gears. It's like having two converters in one!weight: 28t - 60g | 30t - 68g | 32t - 74g | 34t - 83g | 36t - g | 38t - 82g | 40t - 88g | 42t - 96g Material: 7075-T6 aluminum Made in the USA