These trucks come in a pair of two.

• 143's has a 7.125" Axle - for boards 7.4" and thinner
• 145's has a 7.62" Axle - for boards 7.4" to 7.9"
  
• 147's has a 8" Axle - for boards 7.9" to 8.12"
  
• 148's has a 8.25" Axle - for boards 8.12" to 8.38"
  
• 149's has a 8.5" Axle - for boards 8.38" to 8.62"
  
• 151's has a 8.75" Axle - for boards 8.62" and bigger