Climbing karabiner buying guide: Shapes, classifications and colours

September 15, 2023

Climbing karabiner buying guide: Key features explained

The beauty of the karabiner lies in its simplicity. These small, straightforward devices allow climbers to easily create a link between rope and device, attach themselves to their climbing system, or secure additional equipment to their harness. But there’s more to karabiners than meets the eye. They may all look similar, but in reality there are a number of different designs to choose from, all with their own unique pros and cons. 

Whether you’re looking to buy your first ever set of climbing karabiners or are planning to upgrade your current ones, this guide is here to help you choose the karabiner that’s right for you. We’re going to cover all the basics, including shape, colour, classification and more. 


All modern climbing karabiners fall into two categories: either aluminium or steel. Steel karabiners are very strong and are used for rigging or lowering. The high breaking strain makes them compatible with the heavy loads at play in rigging systems, but they’re too heavy and unnecessarily cumbersome for climbing. Aluminium karabiners are the correct choice for climbing due to the low weight, more-than-adequate strength, durability and their compatibility with other components typically found in climbing systems. They also don’t corrode like steel, making them perfect for year-round use. 


All karabiners used for climbing or rigging should comply with the EN362 standard, the quality mark that ensures they’re safe and compliant for arboricultural use. To accompany this classification, each karabiner should bear a unique serial number and must have a strength rating.

Strength rating

Minimum breaking strain, or MBS, is the measurement most commonly used to assess the strength of a karabiner. It’s typically given in kiloNewtons (kN), and gives you an idea of how much gravitational force the device can withstand before it lets go. Naturally, the higher the MBS, the stronger the karabiner. Climbing karabiners must have an MBS of 20kN. Rigging karabiners usually have an MBS of between 35kN and 70kN, and it is the user’s responsibility to select a karabiner that has an appropriate strength for the job in hand, based on the loads at play in the specific scenario.  


When you’re shopping for climbing karabiners, most will more or less fall into one of two shape types: oval or HMS (otherwise known as ‘classic’ or ‘pear’ shaped). There’s no right or wrong choice here – mainly, it all comes down to personal preference. The benefits of HMS karabiners are that they will generally allow the gate to open wider due to the shape, they have a bigger internal space to take more or bulkier equipment, and they’re a bit larger to hold in the hand, which for bigger hands makes them a little easier to open. They’re ideal for use with belaying and anchoring systems, too. 

Oval karabiners, meanwhile, are great for situations where you want the karabiner to sit symmetrically in a system such as a friction hitch; the smooth and consistent curve of the oval shape also means that it will usually move move freely and easily around a device that has a small eye (such as some rope grabs) where the sharper bends and/or ‘kinks’ in a HMS type karabiner can jam. Lastly, some devices such as the Petzl Zigzag specifically stipulate that they should be used with an oval karabiner. 


This comes down to personal choice. Colour coding can be used to either assign particular karabiners to specific items of kit, making them easy to find and identify, or also to identify which kit or person they belong to within a team. There’s no particular guidance as to which colours are normally used for any application, so you have free choice to colour code as is appropriate to you!

We hope this guide has helped you identify the best climbing karabiner for your needs. As you can tell, there’s no one size fits all solution – it largely depends on personal preference and your intended usage. To find your perfect product, take a look at our full range of arborist karabiners today.