Metric Allen Hex keys 1.5 - 22mm Hexagon Allan Alan Key Long Arm Wrench CR-V

Measure the width across the flats of the hex socket (the internal hexagonal recess) using a caliper or a sizing gauge. The measurement in millimeters corresponds directly to the key size — for example, a 5 mm socket requires a 5 mm hex key. If you don't have a caliper, try keys from smallest to largest until one seats fully without play.

The long arm gives you extended reach into deep or recessed bolt heads that a short arm cannot access. When you flip the key and use the short arm as the driver, the longer lever arm of the handle side significantly increases the torque you can apply — useful for loosening seized fasteners. The trade-off is that the long arm requires more clearance to swing.

Chrome Vanadium Steel is a widely used alloy for hand tools because it combines good tensile strength with toughness, meaning it resists both bending and sudden impact. For typical DIY and light-to-medium professional use — furniture assembly, bicycle maintenance, machinery servicing — CR-V hex keys perform reliably. For sustained industrial torque beyond the tool's rated capacity, a torque-limiting tool is recommended to avoid overloading any hand key.

CR-V steel has moderate corrosion resistance, but it is not stainless. To extend service life, wipe keys dry after use, store them away from moisture, and apply a light coat of machine oil if they will be stored long-term or used in humid environments. Avoid prolonged contact with salt water or harsh chemicals.

These keys are sized in metric millimeters and are intended for metric hex fasteners. While some metric sizes are close to SAE equivalents (e.g., 5 mm is close to 3/16 in), using a metric key on an imperial fastener — or vice versa — risks rounding out the socket. For SAE fasteners, use a dedicated SAE hex key set.

Select the specific Key Size you need and choose the 1 pcs Pack Size option (available for 3 mm and larger sizes). This lets you replace a single lost or damaged key without purchasing duplicates. For workshop stock or shared toolboxes, the 5 pcs or 10 pcs packs offer a lower per-unit cost.

These keys feature a chamfered tip that allows angled insertion of approximately 25°, similar in function to a ball-end key for moderate off-axis access. They are not full ball-end keys, so for applications requiring insertion angles greater than 25°, a dedicated ball-end hex key set would be more appropriate.