Whether you call it an Allen wrench, an Allen key, or a hex key, this humble L-shaped legend is one of the hardest-working bits of steel in any toolbox. It might look simple, basically a hexagonal rod bent into an “L”, but it’s a torque-wielding powerhouse that makes light work of hex-socket screws and bolts.
From flat-pack furniture to precision bike repairs, the Allen wrench is the quiet achiever of the tool world. Let’s break down what it is, the different types, the key sizes, and when to reach for each one.
An Allen wrench is a hexagon-shaped steel rod bent at a right angle, giving you two arms of different lengths. The short arm slots into the screw head while the long arm becomes your handle, letting you crank out impressive torque without a bulky handle getting in the way.
The flat faces of the hex fit snugly into the screw’s socket, so you can tighten or loosen with less chance of stripping the head. These tools are typically made from strong, heat-treated steel to handle repeated use without warping.
You’ll see them everywhere, from metal and plastic work to wood projects, and you’ve definitely met one if you’ve ever built a flat-pack bookshelf. The design is beginner-friendly, cheap to produce, and tough enough for pro tradies.
Allen wrenches come in more flavours than a servo pie warmer. Here’s your quick guide.
The classic you’ll find in every hardware store. Looks like an “L”, perfect for tight spaces and solid control. Available in short arm and long arm versions, grab a 1.5–10mm set for a solid all-rounder.
Shaped like a “T” for fast spinning and comfy grip. A favourite for bike mechanics and motorsport techs who need speed and leverage.
A modern twist on the L-style, with a grip at the bend for extra comfort. These often show up in professional workshops where you’re cranking all day.
Think pocket knife for hex keys. Each key folds into a plastic or metal handle and locks at 90° or 180°, so you can reach awkward fasteners. Cyclists and motorbike riders love them for on-the-go repairs.
Often built into a T-handle or folding frame, these come with a magnetic bit holder so you can zip screws in and out with minimal effort, ideal when you need speed.
Not a replacement for a hex key but a must when a specific torque setting is critical, like tightening lag screws or delicate machine parts.
Basically a screwdriver with a hex or Torx tip, usually in 1.5–5mm sizes. Perfect when you need low torque and tight clearance.
These feature a ball-shaped tip that lets you work at a 30-degree offset angle, a lifesaver when the screw is tucked away in an awkward corner.
Built with a movable jaw, these come in 200, 250 and 300mm sizes. Great for plumbing, car repairs or anywhere you need to tweak the jaw size to match different fasteners.
This one is double-ended, a box end on one side for a tight grip, and an open end on the other for quick access. A staple in bike repair shops.
U-shaped openings on both ends, sized to fit specific bolts or nuts. Designed for those narrow spaces where larger wrenches can’t squeeze.
A hollow cylindrical head fixed to a handle, sometimes called a ratchet wrench. Delivers speed and efficiency for a variety of bolt sizes.
Like an open-end or box-end but handle-free, with an opening along the rear face so you can slide it sideways onto a nut or bolt. Perfect for cramped spots like power steering fittings, ABS modulators, clutches and brakes.
Allen wrenches come in inch-based sizes and metric sizes. Here is a breakdown of the metric size and inch size of wrenches that match each other.
These compact workhorses turn up everywhere:
Basically, if it’s got a hex socket, there’s an Allen wrench made to tame it.
Allen wrenches are common tools used to turn screws and bolts. They have a beginner-friendly design and are relatively affordable to purchase.
They come in several different types that have different benefits depending on which one you choose, like the adjustable, socket, and combination style wrenches—especially when you're choosing between Allen wrenches vs. Torx wrenches for specific applications.
Tags
When you are working in a workplace where you depend on the right PPE to keep you protected from air pollution, then it’s essential that you can fully depend on your safety gear, so thus, you need the right mask—especially if you’re also deciding between dust masks vs respirators and their proper applications. When it comes
Read MoreHave you found yourself wondering whether you can wear safety glasses over your eyeglasses? Maybe your employer has said that you need to and you want to know if this is true? Or are you curious and want to know more? Whatever the reason might be that brought you here today, we have the answer for
Read MoreThe Diablo tool brand is known for having some of the best power tool accessories, abrasives, and cutting tools for use by trade professionals need tools that can be used at high speed, or can cut through things like cast iron like the Diablo Steel Demon. Especially when you’re tackling demolition jobs that require a
Read More