143: 7.125 Axle - For boards 7.4 & thinner 145: 7.62 Axle - For boards 7.4 - 7.9 147: 8.0 Axle - For boards 7.9 - 8.12 148: 8.25 Axle - For boards 8.12-8.38 149: 8.5 Axle - For boards 8.38 - 8.62 151: 8.75 Axle - For boards 8.62 -8.86 161: 9.125 Axle - For boards 8.9 & Up QUICK RESPONSE, LIGHTWEIGHT AND GUARANTEED STRONG.