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ArcTeryx SL-340 Harness (Magma)

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Size Guide
ArcTeryx Harnesses Size Chart
ArcTeryx Harness Size Chart

The ArcTeryx SL-340 is a massively compact, Super Light, unisex, sport climbing harness designed to deliver when performing at your limit.

Streamlined, sleek and nimble, the SL-340 has been specifically developed for sport climbing and hard 'head point' style trad ascents. It has been designed with a unisex fit to suit both women and men and to deliver security, agility and freedom of movement when you are performing at your limit.

Hardwearing Burly Double Weave absorbs little to no moisture, dries quickly and is soft against skin. The waistbelt construction is updated with a softer edge that creates less pressure and improves overall comfort. The disciplined design means features are stripped to the essential; at 340g (12 oz), this is THE lightest and most compact Arc'teryx harness.

Warp Strength Technology

WST™ differs from traditional harness construction in that the load is evenly distributed across the entire width of the harness structure rather than loading a single, narrow strip of webbing in the centre or running edge binding, both of which tend to concentrate the pressure of the harness making them less comfortable. Warp Strength Technology™ cradles the body and the load is universally dispersed from edge to edge. This construction method provides a high degree of support and this new generation of harnesses are more comfortable over time and usage than ever before.


  • Wear safety markers on belay loop and tie-in points
  • Self locking buckle
  • WST™ (Warp Strength Technology) load is evenly supported across entire harness 
  • Longer belay loop and thus rise fits both men and women
  • Two gear loops
  • Stretchy mesh storage bag
  • Drop seat
  • Rear haul loop
  • Sure fit elasticised fixed leg loops enable a precision fit with varying layers

Burly™ Double Weave four-way stretch fabric, 7075 T6 aluminum anodized buckle, Type 66 nylon webbing, Polyurethane gear loops

Size Waist Leg
XS   66-74 cm  47-52 cm
S   72-79 cm  51-55 cm
M   78-86 cm  55-59 cm
L   86-96 cm  59-65 cm
XL   96-106 cm  62-69 cm


  • Gender: Unisex
  • Adjustable Legs: No
  • Drop Seat: Yes
  • Gear Loops: 2
  • Haul Loop: Yes
  • Ice Clipper: No
  • Quick Buckles: Yes
  • Weight: 340g (M)

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Anoushka L.
United Kingdom

great harness

very simple and comfortable. light.

stephen l.

High quality and very comfortable

High quality and very comfortable harness. Light.


Pretty much as the reviews

Pretty much as the reviews all say. Super-lightweight and the load is spread better than with padded harnesses so, somewhat surprisingly, is more comfortable too.

David S.

Very impressed with the harness,

Very impressed with the harness, comfortable belaying, lowering or falling. good gear loops. Service was superb, good info for choice, very quick delivery.

Miguel s.

The rocknrun service was excellent.

The rocknrun service was excellent. The harness though is not as brilliant as expected for a top price harness. The size is ridiculous, I use to wear M or S, I took the measurements and read the sizing chart and ordered an S, and the harness is big for me. I'm a male 187 cm and 70 kg, stunning to know I wear XS. I also bought that harness because I have back pain and I've been recommended because the thick back support, but my feeling is worse than with my petzl corax. Nevertheless is reaaally light, and comfortable if you get the proper size.


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