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

Specs:

Teeth: 19/23

4.11 Gear Ratio: Low 3.40 High 4.98

4.12 Gear Ratio: Low 3.40 High 4.99

4.57 Gear Ratio: Low 3.78 High 5.53

4.86 Gear Ratio: Low 4.0 High 5.88

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