Original equipment carbon fiber VForce4R replacement reed petals exclusively for the VForce4R reed valve system. Are you checking your reed petals for signs of normal wear? You should be. A reed petal is a wear item, and as such should be checked regularly for signs of wear and fraying. A reed petal is opening and closing 144 times per second at 8,000 RPM, so it&';s understandable reeds can wear. If wear and/or fraying is visible, it&';s time to replace your reed petals to maintain peak engine performance. Please note: Replacement reed petals are sold in complete sets of four, which is enough to replace all the reed petals on one reed cage assembly.