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Tech Specs Of Half Balls For Your Wobble Board And Rocker Board

Si Boards Half Balls create a stable pivot point to balance. Your half ball will last a lifetime and is ready for you to customize your training.

Urethane Material:

  • Solid urethane with no air, gel or sand filling to break open.
  • Exceptional resistance to friction, oils, solvents, UV, extreme temperatures and is odor free.
  • Higher strength and durability compared to rubber, plastic or vinyl.


  • Made as one complete unit and avoids seams or piecing together.
  • 3" and 5" half balls are completely flat on the bottom.
  • 6.5" and 8.5" half balls have a recessed are on the flat side.


  • Slight tacky feel with grip bumps for texture.
  • Easily grips the board and ground surfaces for safety.
  • Will not slip on carpet or tile floors compared to wood or plastic pivot points.


  • Very stiff with slight flexibility.
  • Best described as the hardness of a lacrosse ball.
  • Not as hard or slick as a bowling ball.

3" Mini Half Ball:

  • 1.5" height0.5 lbs in weight
  • Used on Kick Start board
  • Offers very little tilt for beginners

5" Small Half Ball:

  • 2.5" height
  • 1.25 lbs in weight
  • Used for beginners on all Starter boards and Ultimate Fitness board

6.5 Medium Half Ball:

  • 3.25" height
  • 2.3 lbs in weight
  • Advanced use on all Starter boards and Ultimate Fitness board
  • Advanced use on Turbo and Powder Original boards

8.5" Large Half Ball:

  • 4.25" height
  • 4.25 lbs in weight
  • Advanced users on Freestyle and Surf Original boards
  • Very advanced for the Ultimate Fitness board
  • Recommended for the Commando board