These precision-machined brass axle caps are designed as a direct upgrade for the Kyosho MX-01 Mini-Z 4x4 rear axle, significantly enhancing the crawler's performance. By adding unsprung weight directly to the rear wheels, they effectively lower the vehicle's center of gravity and improve traction, stability, and crawling capability over challenging terrain. Crafted from durable brass, these caps not only provide a substantial weight advantage for better articulation and reduced rollovers but also offer superior wear resistance compared to stock plastic or lighter metal components, ensuring long-lasting reliability for serious RC enthusiasts.