89-19 YAMAHA YZ250: Factory Connection Shock Spring (6.3 Kg) Factory Connection engineers and creates proprietary spring designs to their own industry-leading standards. Each series of Shock Spring is designed for your specific brand / model shock. The Factory Connection Shock Spring's fitment to each shock body is the absolute best in the industry. The highest tensile strength commercial grade silicone spring wire is used and each unit is pre-inspected.The Factory Connection Shock Spring is cold wound on precision CNC equipment.Heat-tempered, shot-peened and end-ground to improve spring stress and s industry standard of 200,000 cycles; many are tested to 500,000 cycles.Each spring must pass a rigorous 11 category quality assurance inspection process before it is approved for sale.Wide variety of rates and applications are available from Factory Conne