Bones Street Tech Formula Wheels Gravette Sprout 51MM STF /- Pro team STF from Powell are best used for street skating. STF wheels are the hottest wheels around! sold in sets of 4. Features - Diameter: 51mm - Width: 28mm - Hardness: 83B - Formula: STF - Color: White - Core: No - Surface: Treaded - Sugg. Use: Street