Procomp Electronics billet main caps are precision CNC-machined from superior-quality 1025 billet steel. The splayed caps feature 10-degree angled outer holes to positively reinforce and tie the block together. This extreme main cap set consists of the center 3 caps. Procomp Electronics billet main caps improve reliability in highly stressed engines by reducing distortion of the main bearing bores and increasing the cap's resistance to closing up under high loads.