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A buyer’s guide to carabiners – the unsung heroes of climbing


Now it should be quick
Now it should be quick

Carabiners are the unsung heroes of climbing. They get beaten to a pulp and still save thousands of lives each and every day without receiving the slightest bit of gratitude or appreciation for their wonderful form and function. Contrary to popular belief, a carabiner is not just there for you to clip your water bottle to the outside of your pack, your keys to your belt loop or your dog’s leash to its collar. Carabiners have a bigger purpose! They literally allow climbers to do everything from clipping their ropes into protection, to racking gear, to holding falls. They keep us safe and allow us to move efficiently in the vertical world of climbing.

Who invented it?

The first carabiner was invented by the German climber Otto Herzog on the eve of World War I. Around 1921, the first carabiner for climbers was produced and weighed a portly 130 grams (4.5 ounces). Of course, as a result of technological advances, full-strength carabiners are significantly lighter today, weighing in at around 30 grams (1 ounce).

Plus, they come in a wide variety of shapes, designs and models, all of which serve different purposes in the world of climbing. In this entry, we’ll try to clear up some of the chaos surrounding carabiner models and their areas of use.

The construction

Gate: this is the part of the carabiner that opens and shuts.

Spine: this is the longest side of the carabiner, directly opposite the gate.

Nose: the nose is where the gate snaps shut.

Basket: this is where the rope sits when clipped.

Gate opening

This is the largest possible distance from the gate to the nose when open. It is helpful to know how easy a carabiner is to clip with a rope or how much gear can be racked on the carabiner. This is particularly important for climbers with big hands or for ice climbers who wear gloves.


Carabiners are designed to be loaded along the major axis (longitudes), for this is the strongest orientation. However, it is possible for a carabiner to be loaded latitudinally from the gate to the spine, which is referred to as cross-loading. This doesn’t have to be a bad thing, but the carabiner loses quite a bit of its strength, dropping from 20 kN down to 7 kN. So, you should always be careful and try to avoid it.

Gate-open strength

This refers to the strength of a carabiner when open. It can come to an open gate if the carabiner wasn’t closed properly and is nose-hooked or if a rock pushes on the gate in the direction of opening. Even though this rarely occurs, it does indeed occur and is always bad since a carabiner with an open gate only has a strength of 6 kN and can break much more easily.

The gate

There are solid gates and wire gates. The solid gates open and snap shut using a spring mechanism.

The wire gate may look a bit more fragile than its solid counterpart, but it’s not. The upside to wire gates is that they have less mass, making them less likely to open under their own inertia.

Straight or bent

The wire-gate and solid-gate carabiners come in the straight or bent gate variety. The straight version is usually used for the bolt-end of quickdraws. Bent gates, on the other hand, are reserved for the rope-clipping end of a quickdraw.

For quickdraws, you should always use the same carabiner for the bolt-end and another for the rope-end. That’s why many quickdraws consist of two different carabiners so that you can tell them apart. Using one straight and one bent gate on a quickdraw is one possibility.

The nose

The area where the gate and the basket meet and the carabiner closes is very important not only in terms of strength but also in terms of function and application. Many carabiners have a notch in the nose that hooks onto a bar at the top of the gate. This bar gives the carabiners its strength along the major axis.

However, the notch can be problematic. It is prone to catching on things like gear loops or (even worse) a bolt hanger, which is known as a nose hook. In addition, it can be very tedious to dismantle an overhanging route with nose carabiners.

To solve this problem, the keylock closure system was invented. This is where the gate inserts into the nose of the carabiner like a jigsaw piece. This design used to be available only on solid-gate carabiners, but a few companies have developed similar systems for wire-gate carabiners, such as the Salewa Hot G3 Wire Carabiner.

Size and weight

Today, carabiners come in a variety of sizes and weights, and colours and price classes. The size doesn’t make that much of a difference. It is more of a matter of taste and only interesting because it affects weight. And, if you have a lot of them, as the professional climbers among us do, you’ll definitely notice the difference between a bunch of heavy quickdraws and a bunch of light ones


For the most part, two types of material are used: aluminium and steel. Steel carabiners are extremely durable but also relatively heavy. Aluminium carabiners are much lighter and sufficiently durable, so they will last for several years, but they do wear out more quickly than steel.

Steel carabiners are mostly reserved for high-use situations, such as quickdraws and anchors in a gym. Aluminium carabiners should never be fixed on routes!

Understanding strength

A carabiner is designed specifically for the demands of climbing, meaning they will be more than strong enough for their intended and proper use. So, there’s no need to worry about the carabiner’s strength rating, as long as it meets the European standard (EN 12275) or the UIAA. To find this, look for the CE and/or UIAA icons on the spine of your carabiner. According to these standards, a carabiner should have a breaking stress of at least:

  • Major Axis (lengthwise): 20kN
  • Minor Axis: 7 kN
  • Open Gate: 6kN

However, some carabiners exceed the norms. Thus, manufacturers tend to laser-etch or forge the ratings into the body of the carabiner. Here, you’ll find the ratings of the 3 orientations: major axis, minor axis and open gate.

When choosing a carabiner, the strength rating is usually not the main criterion, since all climbing carabiners are significantly stronger than we usually need them to be. But, if you can’t seem to decide between two carabiners, the rating should play a more significant role than, say, the colour.

Shape options

Oval carabiners
This is the original shape of the carabiner, but it is still being produced by some companies. However, they’re hardly being used for climbing anymore. Even though the oval carabiners claim to allow you to rack a lot of gear, they sacrifice strength and are more difficult to use than other carabiners. However, they’re frequently used for tree climbing and industrial applications.
The regular D-shaped carabiners
These are regarded as the second step forward in the evolution of carabiners. Their shape increases their strength and simultaneously makes them easier to use.
Asymmetrical D-shape
Now, it’s getting more interesting. The offset D or asymmetrical D-shaped carabiner allows you to do just about anything, so these should definitely make up 99% of your rack. The asymmetry serves to increase the carabiner’s strength whilst simultaneously reducing the weight. Thus, these carabiners are much lighter than their predecessors. The asymmetry also allows for a larger gate opening than regular Ds, which improves its functionality.
Based on their strength, you could use them for just about anything, but the pear/HMS carabiner is intended to be used with belay/rappel devices. The large basket provides plenty of room for a HMS or Munter hitch, hence the name. But, please keep in mind: not all HMS carabiners should be combined with all belay devices. Always have a look at the manufacturer’s specifications beforehand.
Locking vs. non-locking
Basically, carabiners can be divided into two groups: locking and non-locking carabiners. Non-locking carabiners can be opened as long as there is some kind of pressure applied to the gate. The locking carabiners, on the other hand, feature a locking mechanism. Before it can be opened, a climber would have to “unlock” the carabiner. Within the category of locking carabiners, there are twist lock or auto-locking and screwgate or manual-locking carabiners. Auto-locking can be opened with one hand. There are several different models, but not all are suited for every belay device.
Karabiner verschließbar-nicht verschließbar
left: locking, right: non-locking
Auto-locking or not
Carabiners are divided into two groups: self-locking and auto-locking. Auto-locking carabiners are those that lock automatically without the climber having to do anything, e.g. the Sender Twistlock Carabiner from Mammut. These come in different designs and, again, not all are suitable for every belay device.
left: self-locking, right: auto-locking
A locking system with a plastic clip or without
This kind of locking system cannot be opened without the climber doing something. Other carabiners without the plastic clip locking system can unlock themselves as a result of a jolt. As improbable as it may seem, it has happened a number of times. Thus, a twist-lock carabiner shouldn’t be used for belaying with a HMS carabiner.
left: keylock, right: gate with nose

So, which one should you pick?

First, you should decide on a shape, such as ‘D’ or pear-shaped. Second, would you like it to be locking or non-locking? What about the gate: solid or wire gate? It is important to think about what you’ll be using it for as well: belaying, quickdraws or racking gear? Would you like to be able to operate and open the carabiner with one hand or two?

What about the colour? The colour really makes sense when you have the same model on each end of a quickdraw and would like to be able to immediately distinguish which side is for the rope.

Lastly, it’s always a good idea to try out different carabiners to see which ones work best for you!

Which carabiner do I use for a sling? A HMS carabiner is suitable for a sling. You can attach the webbed sling to this.
Which carabiner do I use for a Grigri? When belaying with a Grigri, you can use many types of carabiners. For example, a HMS carabiner like the DMM Belay Master 2 is a good choice. This also has the advantage that the carabiner cannot twist due to its construction.
How many kilograms can a carabiner withstand? How much a carabiner can withstand depends entirely on how many kN the respective carabiner has, whether there is a longitudinal, transverse or open load and for which purposes it is designed. For example, you should never use a mini carabiner to attach a water bottle to your backpack for climbing.

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