BILSTEIN HD: This is the heavy duty version of Bilstein shocks. This shock is closer to the stiffer suspension of an SPG/Viggen/AERO that Saab offers.
About Bilstein: Bilstein was first to apply the patented gas pressure principle to controlling ride characteristics on automobiles and introduced the world's first monotube gas pressure shock absorber. Today, Bilstein continues to be the leader in monotube gas pressure shock absorber technology. No other manufacturer has been able to equal the performance and enhanced ride characteristics of Bilstein.