The KYB Gas-a-Just monotube truck shock absorber has additional performance advantages over the twin-tube design: It can instantly, automatically adjust to your performance needs and never experiences fade due to aeration. The Gas-a-Just is available as an OE monotube replacement and as an OE twin-tube performance upgrade. The KYB Gas-a-Just has two separate working chambers: An air-free hydraulic piston and valve area for responsiveness & control, and a second high-pressure nitrogen gas area with a floating piston that provides a comfortable ride during normal driving and adds instant performance on demand. Provides up to 25% more damping control over original equipment shocks Gas-a-Just reacts to load changes and adds instant responsiveness on trucks High gas pressure design is perfect for hauling heavy loads monotube design outperforms all other standard shock absorbers Unique, air-free, hydraulic unit eliminates performance fade