Progressive Suspension 04140388 Fork springsRef : PRSU00002A / 04140388

Progressive Suspension Kit monotube cartridge (manufacturer part number: 31-2504) — fork cartridge kit designed to replace the dual tube system with a high-performance monotube cartridge. Designed for touring motorcycles, it combines monotube gas cartridges and custom fork springs for a smoother and more controlled ride.

This kit improves dive resistance during braking, front stability, cornering grip, and bottoming management without requiring internal modifications to the fork. Made in the USA, it is available in a lowering version that lowers the front by up to 50.8 mm (2.00"); please note, the lowering version is not compatible with "Low" models.

• Fork tube diameter: 41.00 mm (1.61")
• Height adjustment: lowers 50.80 mm (2.00") (lowering version)
• Style: Monotube
• Unit: Complete kit (cartridges + springs)
• Manufacturing: USA

Common installation examples: Harley-Davidson FLSTFBS Fat Boy S (2017), FLSS Softail Slim S (2017), FLSTN Softail Deluxe (2017). This kit is aimed at riders looking to firm up the front, reduce bottoming, and gain precision in road handling.