10-1875 Color / Level: Black / X-Hard Features: -Offer an unstable and sensory-stimulating platform to facilitate balance.-Can be used for: balance, coordination and proprioceptive training.-Three stainless-steel insets on the bottom to accommodate the screw-in instability ball(s).-Used as a rocker simply insert two balls into the stainless-steel insets on the bottom of the board.-Allow the board to move in only one plane of instability.-Used as a wobble board place one ball in either the center inset or in one of the extremity insets.