Sold as two bushings.

WFB or Worlds Fastest Bushing- is a special formulation of urethane where there is a lubricant mixed in to the urethane.  Which is why these bushings will sometime look a little crusty.

The result is an even deeper turn than the APS allows.  So if you are looking for a bushing that is supportive but still allows full controlled deep turns, then throw some of that WFB into the mix.

A lot of riders feel the double barrel (Barrel bushings on road side and board side) give just the right amount of return to center support and break from center feel.