The KYB Gas-a-Just monotube shock has two possible purposes. First, it's a direct Original Equipment (OE) replacement if your vehicle came with a monotube shock absorber from the factory. Second, the KYB Gas-a-Just is also a performance upgrade for vehicles that came factory-equipped with a twin-tube. Upgrading from twin-tube to monotube shocks can increase steering responsiveness by as much as 30%. The monotube design never experiences shock fade, and the high gas pressure can automatically add performance for more aggressive driving conditions or for heavier loads. Whether as a replacement for your original monotube shock absorbers or as an upgrade from your original twin-tube shock absorbers, the KYB Gas-a-Just is an excellent choice.