These premium distributors include Genuine GM Performance Parts melonized gears, which are required on all GM Performance Parts crate engines, or serious damage will occur. Sintered steel weights for lighter weight while withstanding 270 newtons min. for maximum durability. Validated harness and capacitor for reliable energy flow. Adjustable vacuum advance for fine tuning the rate and amount of advance that will result in increased power and eliminate harmful detonation. Weight springs made with stress-relieved music wire to assure blueprinted advance curve. High-performance module is engineered with low saturation for maximum spark intensity. Low-friction cam with super-smooth, gradual, tight tolerance TIR or Total Indicated Runout deviation from datum line. Bronze sintered bushings precisely installed and line- honed for perfect positioning. Durable, centerless ground coated shaft for reliable energy transfer and long-term, trouble-free performance. Final Assembly and Individual Inspection In Warren, Michigan. Officially Licensed GM Performance Parts Product. Sold individually.