Lifetime Manufacturer's Precision wound Progressive Rate Some applications are offered in Heavy Duty and Standard Versions. Progressive Suspension Front Fork Spring Kit for Harley Davidson FXDB-D/FXDC 1992 / FXDB-S 1991 / FXDL 1993 / FXDL 1993-2205 / FXDLI 2004-2005 / FXDS-Conv 1994-2000 / FXDX 1999 / FXRS-Conv 1990 -1993 / 1987-1993 FXRS-SP / 1988-1992 FXRT - Pair - Black - 11-1132 Progressive springs offer a soft initial spring rate for a plush ride. The progressive design provides increased resistance to bottoming out as the force compresses. spring. Improves handling while maintaining OEM geometry. Made in the USA