H&R Special Springs are high quality products—they will not set or sag, they are designed and manufactured to be strong, resilient, and more durable than other automotive coil springs. All H&R springs are crafted from a special (hf) 54SiCr6 spring steel to ensure premium quality and performance. H&R Springs are shot-peened to increase their life by more than 200%. All production is completed in-house so product quality is ensured. Each spring is 100% tested before leaving H&R's ISO9001 certified production facility in Germany.