Robust companions for any type of climbing: Sewn runners
They definitely are a must have in every climbers basic equipment - and that too, more than once! Sewn runners are extremely versatile and can be used to pull intermediate points (hourglass outcrops), as well as for self-belay or hanging a hammock on trees!
They are also often called "Sewn slings" That´s because slings are often roundly woven tube straps (and not because they are stitched into circles). As an advantage, sewn runners are narrower on a consistent breaking load than flat webbings.
Here you can find more information on sewn runners, as well as some advice on how to choose the right version.
General facts about slings
Sewn runners for climbing are either always made of polyamide (usually nylon) or polyethylene.
The former version is a little cheaper, and since its outside is matte, loops fit and stay extremely good. Here you can get robust slings that offer a great value for money.
However, a sling made of polyethylene (usually dyneema by DSM) offers much higher durability with the same amount of load, and has a smaller material cross-section. Although, dyneema slings can be knot more easily, they can also open up very easily since their outside is much smoother - therefore, one needs to be cautious! Due to their low weight and high durability, these versions are extremely suitable for ambitious sports climbing, multipitch route touring, as well as alpine and ice climbing
Generally, sewn runners are static and as a rule, they have a breaking load of 22kN. Usually, a color coding helps to gain and maintain an overview.
Use and variations of sewn runners
Slings are available in different widths (from approx. 8mm to 16mm) and various lengths as well. These range from 30 cm to 60 cm, 80cm 1.2m, 1.8m and even 2.4m.
The usual length for a self-belay is 60 or 80 cm. 1.2 m or a particular belay sling are required for the construction of a pitch. You should carry various lengths (30-80cm, depending on the rock structure) for intermediate connection points.
Long versions are great to fix hammocks. They also serve as accessories for slacklines (slackline-backup or a loop around a tree).
Sewn runners such as daisy chains (gear sling with a lot of loops) especially, round off the range of goods and provide you with organization.