Progressive Suspension 444-4021C 444 Series FST Rear Shock Absorbers

Progressive Suspension's 444 Series rear shock absorbers build on the legendary success of the 440 Series by introducing Frequency Sensing Technology (FST) — an innovative damping system that automatically adjusts to road conditions as you ride. These shocks deliver a superior, more responsive ride without the need for manual adjustments mid-trip.

Frequency Sensing Technology (FST) works by detecting the frequency of each bump and dynamically tuning damping response in real time. Low-frequency inputs (large bumps) receive softer damping for comfort, while high-frequency inputs (small, rapid chatter) receive firmer damping for control — all without any rider intervention.

Key Features:

• Frequency Sensing Technology (FST) — automatic, dynamic damping adjustment based on bump frequency
• Deflective disc valving for smooth, consistent damping performance
• Hand-adjustable spring preload — no special tools required
• Progressive rate springs for a compliant ride at low loads and firm support under heavy loads
• High-pressure gas charge for fade-free, consistent performance mile after mile
• Sold in pairs — complete replacement set for both sides
• Lifetime Limited Warranty included

Whether you're cruising the highway or carving through back roads, the Progressive Suspension 444 Series shocks offer a significant upgrade in both ride comfort and handling precision over stock OEM shock absorbers.