Winters Quick Change Gears are constructed from SAE 8620 Steel, Crown Cut, 1-3/8" Wide. 

Specs:

Teeth: 17/28

4.11 Gear Ratio: Low 2.50 High 6.77

4.12 Gear Ratio: Low 2.50 High 6.79

4.57 Gear Ratio: Low 2.77 High 7.53

4.86 Gear Ratio: Low 2.95 High 8.00

To see other gear sets available, check out the Winters Quick Change Gear Chart