SUPER Grippy. Trish loved them on super slippery surfaces, like TRD's Catalina High track and Sin City's slippery polished cement before it was painted. They are the grippiest indoor speed wheels we ever tried. Extra grippy - too grippy for us, especially jamming - on nubby sport court. Good all-around derby wheels for most surfaces; GREAT on slippery surfaces.
520 urethane formula (compare to Poly BD)