SS M4x40L Allen Head Screws (10pcs)
The SS M4 x 40mm Allen Socket Head Screw is a heavy-duty precision fastener designed for structural applications requiring an extended reach and high clamping force. Manufactured from premium Grade 304 Stainless Steel (SS304), these screws offer superior resistance to corrosion, rust, and chemical wear. The cylindrical socket head design is specifically engineered for use in tight spaces or recessed cavities where traditional hex-head bolts cannot be reached by a wrench.
Key Features
Equipped with a hexagonal internal drive, these screws are tightened using a standard 3mm Allen Key. This internal drive system allows for significantly higher torque and more secure fastening compared to standard Phillips or slotted screws, virtually eliminating the risk of head stripping. With a 4mm diameter and a substantial 40mm length, these screws are ideal for through-hole mounting and securing thick multi-layered assemblies.
Versatile Applications
The M4 x 40mm sizing is a staple in high-performance mechanical and DIY projects:
Robotics & Heavy Drones: Perfect for securing motor mounts on thick carbon fiber arms or connecting structural frame spacers.
3D Printing: Frequently used for mounting larger stepper motors, frame joinery, and heavy-duty axis components.
Automotive & Marine: Essential for securing sensors, internal modules, and hardware in environments exposed to moisture or salt.
Machinery Assembly: Providing a stable, vibration-resistant connection for precision instruments and industrial enclosures.














