(you will be contacted via email) The Evolution of HPA Performance The FEROX is a premium CNC-machined aluminum upper receiver engineered specifically for HPA builds where reliability, consistency, and ease of maintenance are essential. Designed and manufactured from high-grade aluminum with precision CNC machining, FEROX is available in multiple anodized finishes and is compatible with most M4 platform lowers on the market. Unlike traditional upper receivers, FEROX has been designed around the HPA system, creating a rigid structure that guarantees perfect alignment between the HPA engine, hop-up chamber, and inner barrel. Perfect Alignment. Every Time. One of the biggest challenges of HPA builds is maintaining the correct alignment between the engine and the hop-up. FEROX solves this problem with a dedicated mechanical positioning system. Once the initial setup has been completed, every component always returns to its exact position after maintenance, eliminating the need for repeated adjustments and ensuring consistent feeding and air seal. No more trial-and-error.No more constant tuning.Simply consistent performance. Fast Maintenance Maintenance has never been easier. Only 3 screws are required to access the HPA engine directly. The complete front assembly can be removed by loosening just 2 additional screws, allowing quick access to the hop-up chamber and inner barrel. This dramatically reduces maintenance time during both practice and competition. Quick Release Hop-Up System FEROX includes an innovative quick-release hop-up system designed to: Precisely position the hop-up with your preferred magazines Maintain repeatable alignment after every disassembly Allow fast removal for cleaning or maintenance Eliminate unwanted movement during use The result is greater consistency, improved reliability, and easier servicing. CNC Construction Every FEROX upper is precision CNC machined from aluminum and finished with high-quality anodizing. Compared to the SKP Carbon Fiber Upper, the aluminum version weighs approximately 50 grams more, providing increased rigidity and durability while maintaining excellent handling. Compatibility Compatible HPA Engines PolarStar F2 PolarStar JACK Wolverine Inferno Compatible Hop-Up Chambers Maxx Model (recommended) Nexx Speed (recommended) PolarStar Retro Arms and most M4-compatible hop-up units Compatible Lowers Compatible with most M4 platform lowers. Best performance is achieved with: SKP Lower SKP Gearbox PolarStar F2 Engine Maxx Model Hop-Up Nexx Speed Hop-Up Package Includes FEROX Front FEROX Back Engine mounting plate Rear endcap bushing Front bushing CNC Front Sight Aluminum Magic Pin Quick-release hop-up mounting system Complete mounting screws Important Compatibility Notice FEROX requires the lower half of an HPA gearbox, such as the SKP Gearbox, to function correctly. Please ensure your build includes a compatible lower gearbox shell before purchasing. Key Features CNC-machined aluminum construction Multiple anodized color options Perfect engine-to-hop-up alignment Fixed positioning system for repeatable assembly Direct engine access with only 3 screws Front assembly removable with only 2 screws Quick-release hop-up system Compatible with most M4 lowers Designed specifically for competitive HPA builds Built for reliability, precision, and fast maintenance FEROX isn't just another upper receiver—it's a complete HPA platform engineered to maximize consistency, simplify maintenance, and deliver uncompromising performance on the field.
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