It Is The Touring Car Spring For The Racing Performer Series, Which Was Also Attached To The World Champion Machine BD8 That Won The World Championship. The Pitch Of The Wire Winding Changes Within A Single Spring, Making It A Progressive Type That Combines Hardness And Softness. It Comes In A Chic Black Color, With The Hardness Laser Engraved On The Ends Of The Spring. Comes In A Dedicated Plastic Case.