Metric Short Arm Allen Keys-Hex Wrench-Hexagon Key 1.5mm - 17mm All Sizes

A flat head (standard) hex key must be inserted straight into the fastener socket — it delivers full torque and is the correct choice for high-torque applications. A ball head key has a rounded tip that allows engagement at angles of approximately 25–30° off the fastener axis, which is useful when you cannot align the wrench directly with the bolt. For maximum torque, always use the flat end of a ball head key or choose a flat head key.

Short arm Allen keys are designed for situations where the surrounding structure limits how far a wrench can extend. Common examples include recessed bolt pockets in bicycle frames, fasteners inside equipment housings, and furniture joints where the adjacent panel blocks a long arm. The trade-off is that the short arm provides less torque leverage on the driving end, so they are best suited for moderate-torque fasteners.

Match the hex key size to the across-flats (AF) dimension of your fastener's socket — this is typically stamped on the fastener head or listed in the product's assembly manual. Common sizes: M3 screws use a 2.5 mm key; M4 use 3 mm; M5 use 4 mm; M6 use 5 mm; M8 use 6 mm; M10 use 8 mm. If you are unsure, measure the socket width with a caliper before ordering.

Yes. Short arm Allen keys are widely used in bicycle maintenance for stem bolts, handlebar clamps, derailleur limit screws, bottle cage bolts, and saddle rail clamps. The 2.0 mm, 2.5 mm, 3.0 mm, 4.0 mm, 5.0 mm, and 6.0 mm sizes cover the majority of hex fasteners found on road and mountain bikes. The ball head option is particularly useful for reaching angled bolts on integrated cockpits.

These keys use a black oxide surface treatment over chrome vanadium steel. Black oxide provides moderate corrosion resistance suitable for typical workshop and occasional outdoor use. For prolonged exposure to moisture or salt environments, wipe the keys with a light machine oil after use and store them in a dry location. Black oxide is not equivalent to stainless steel or zinc plating in terms of corrosion resistance.

These are metric-sized keys and are not interchangeable with SAE (imperial) hex fasteners. Using a metric key on a close-but-not-matching imperial fastener — or vice versa — risks rounding the socket. Always confirm whether your fastener uses metric (mm) or imperial (inch) sizing before selecting a key. If you need SAE hex keys, please contact us to confirm availability.

If you need a single replacement for a lost or worn key, the 1 pc option is the most economical choice. The 5 pc and 10 pc packs offer a lower per-unit cost and are practical for service benches, tool kits shared among multiple users, or resale. The 2 pc option suits situations where you want a spare on hand without committing to a larger quantity.