Grub Screws with Internal Hex Head (Under Head Allen Key Bolts) are designed for secure, flush fastening without protrusions, making them ideal for mechanical and precision applications. Available in 3mm, 4mm, 5mm, 6mm, and 8mm sizes, these screws feature an internal hex socket for a firm grip using an Allen key. Perfect for securing gears, pulleys, and shafts, they provide a strong hold without damaging the surface. Made from high-strength, corrosion-resistant steel, they?re reliable for industrial, automotive, and DIY projects. Whether you're a professional or hobbyist, these versatile grub screws ensure stability and long-lasting performance.