L Shaped Hexagon Key Allen Wrench Screws High Strength Class 12.9 45 Gauge Steel

Class 12.9 refers to the mechanical strength grade of the steel. It indicates a minimum tensile strength of approximately 1,220 MPa and a proof load stress of around 1,100 MPa. Standard consumer-grade hex keys are often made from lower-grade steel (e.g., S2 or Cr-V), which can deform or snap under high torque. Class 12.9 keys are suited for industrial and precision applications where consistent torque is critical.

Match the hex key size to the socket opening of your bolt head. Common pairings: M3 bolt typically uses a 2.5 mm hex key; M4 uses 3 mm; M5 uses 4 mm; M6 uses 5 mm; M8 uses 6 mm. If you are unsure, the 8-piece or 11-piece set covers the full M2–M8 range so you always have the right size on hand.

No. These are metric hex keys designed for ISO metric socket screws. SAE (inch) fasteners use different socket dimensions (e.g., 3/32", 1/8", 5/32"). Using a metric key on an SAE fastener — or vice versa — risks rounding out the socket. Please confirm your fastener standard before ordering.

Machine meter screws, also called socket set screws or grub screws, are fully threaded fasteners with no external head. They are driven entirely by a hex key and are used to secure a component onto a shaft (e.g., a gear, pulley, or knob) by applying clamping force through the tip. Common applications include motor shafts, CNC spindles, and adjustable mechanical assemblies.

The surface treatment provides moderate protection against rust in typical indoor workshop conditions. For prolonged outdoor exposure or high-humidity environments, we recommend applying a light coat of machine oil after use and storing in a dry location. For fully corrosion-resistant fasteners in marine or outdoor applications, consider stainless steel alternatives.

These are manual L-shaped hex keys and are not designed for use with power tools. For power tool use, you would need a hex bit (also called an Allen bit) that fits into a drill chuck or impact driver. Using an L-key with a power tool risks bending the key or damaging the fastener socket.

If you already know the exact size you need for a specific repair or project, buying an individual key is the most cost-effective option. If you work across multiple projects or maintain equipment with varied fastener sizes, the 8-piece set (covering common sizes) or the 11-piece set (broader coverage) ensures you are never caught without the right tool. The 10-piece screw packs are ideal when you need both the tool and replacement fasteners for a specific size.