Bushing type. A true sport performance shock at heart with competitive price. The Progressive Suspension 494 Sport Series Shocks feature a high-pressure nitrogen charged monotube design with deflective disc damping technology; hand threaded preload; and a rebound adjustment to dial in the ride. This technology coupled with a progressive rate spring allows for a consistent performing shock in a variety of real-world scenarios. An engineered jounce bumper with a built-in metal cup helps smooth out and control bottoming. From pounding the pavement around town to hammering around the tarmac on your next race day; the 494 is the perfect choice for your performance demand! Every shock is hand-built; tuned and checked for a bolt-on non-issue shock experience. - High-pressure monotube design - Deflective disc damping technology - Jounce bumper with a built-in metal cup against bottoming out - Hand adjustable spring preload - Progressive rate spring. What are Progressive Suspension''s ''STD Duty'' vs ''Heavy Duty'' or ''Super Heavy Duty'' shocks? If you are a lightweight rider with a lightweight passenger; STD Duty is probably your best choice; heavy duty shocks will give you a harsh ride. For Big Guys & Gals with a lot of baggage; Heavy Duty springs are the way to go. Heavy Duty is not better; it''s different.Heavy Duty shocks or springs are recommended to be used on motorcycles that are operated at or near the manufacturers maximum load rating over 50% of the time. In short: Standa