Bones Skate Park Formula PoPo Wheels 53MM SPF - Bones wheels from Powell are specially formulated for park skating. Designed specially to avoid flat spotting and chipping bones wheels are the best wheels for any park skater! sold in sets of 4. Features - Diameter: 51mm - Width: 28mm - Hardness: 84B - Formula: SPF - Color: White - Core: No - Surface: Treaded - Sugg. Use: Park