Progressive Suspension PS-11-1552 Heavy Duty Fork Spring Kit for Harley-Davidson Sportster 04-21 w/39mm Fork Tubes & Street 500 15-20 w/37mm Fork TubesDescription for Progressive Suspension Heavy Duty Fork Spring Kit 11 1552 An all new heavy duty version of the Progressive Suspension fork springs Substantially increases front end ride quality Progressive Suspension rate springs combined with preload spacers are included Improves front end stability and brake dive control Also increases comfort for heavier riders or those looking for a firm high performance feel out of their forks Included Items: (2)