Durable Construction: Spun aluminum inner mud plug designed specifically for 15" left rear wheels., Multiple Bolt Patterns: Drilled for compatibility with 5 on 4-1/2", 4-3/4", and 5 on 5" bolt patterns., Racing Utility: An essential addition for dirt circle track cars including Modifieds, Sport Mod, and Street Stocks., Enhanced Defense: Can be combined with mud repellent sprays to prevent unbalanced wheels from mud buildup., Compatibility Notes: Available in 2", 3", and 4" offsets but does NOT fit Wide 5 bolt patterns; 3" and 4" versions are not suitable for GM 7.5" rear disc brake kit applications.