A sling or runner is an item of climbing equipment

Climbing equipment

A wide range of equipment is used during rock climbing. The most popular types of climbing equipment are briefly described in this article. The article on protecting a climb describes equipment commonly used to protect a climber against the consequences of a fall....

 consisting of a tied or sewn loop of webbing

Webbing

Webbing is a strong fabric woven as a flat strip or tube of varying width and fibres often used in place of rope. The name webbing comes from the meshed material frequently used in its construction, which resembles a web...

 that can be wrapped around sections of rock, hitched (tied) to other pieces of equipment or tied directly to a tensioned line using a prusik knot; for anchor extension (to reduce rope drag

Rope drag

In rock climbing, rope drag is the friction of the rope plus its weight that the climber feels when pulling a rope through a number of protection points, or over rock prominences...

 and for other purposes), equalization, or climbing the rope.

Short slings are a component of quickdraw

Quickdraw

Quickdraws are used by rock climbers to connect the climbing rope to bolt anchors or other protection, while lead climbing...

s; sometimes known as 'dogbones'. Sewn slings are sold in a range of lengths, such as 10 cm, 30 cm, 60 cm, 120 cm or 240 cm, and in widths of 6–20 mm. Sling tape is also sold off the reel, usually per meter, so that climbers can assemble their own slings by cutting tape to length (with a hot knife to prevent fraying) and tying the ends, typically using a tape knot. Sewn slings have a rated breaking strength of at least 22 kN.

In recent years, slings made from ultra high molecular weight polyethylene

Ultra high molecular weight polyethylene

Ultra-high-molecular-weight polyethylene , also known as high-modulus polyethylene or high-performance polyethylene , is a subset of the thermoplastic polyethylene. It has extremely long chains, with molecular weight numbering in the millions, usually between 2 and 6 million...

 sold under the brand names Dyneema, Dynex and Spectra. It has a much lower melting point than nylon, making it a potentially poor choice for prusiks. However it is lighter, smaller, and absorbs less water than the traditional nylon

Nylon

Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...

sling, and therefore has become popular.

A gear sling is used to organize or carry equipment; these can be pieces of custom equipment which are meant only to carry light gear and are therefore not load-bearing, or they can simply be a regular sling used to rack gear.