Optimize your 223/5.56 Rifle's performance with the Strike Industries SI-AR-LRSK-PRO M4 Lower Receiver Spring Kit. This indispensable 20-piece set offers essential components for smooth and reliable operation. Constructed from premium, corrosion-resistant materials, this kit ensures durability and long-lasting functionality. Each spring is meticulously designed for effortless customization of your lower receiver. 20-piece comprehensive spring kit Compatible with various lower receiver configurations Corrosion-resistant materials for enhanced durability Designed for easy installation and maintenance Improves trigger pull and overall firearm mechanics Enhance your shooting precision and reliability with the Strike Industries Spring Kit for your 223/5.56 Rifle.