The Metolius Open Loop Sling is our Top Pick for anchor building because it is easier than any other sling that we tested to untie knots after they have been weighted, a critical component to any anchor building sling, and one that will be greatly appreciated by anyone who has battled to loosen a welded knot while trying to quickly leave the belay. It also comes in the widest variety of both widths and lengths of any that we reviewed here up to 480cm (16' long!), allowing for the greatest amount of customization to your anchor building needs. We tested the 11mm wide, 120cm long version, which allowed us to easily equalize two anchor pieces with a figure-eight knot. While many other slings will also work for this purpose, we are convinced that the Open Loop Sling is the ideal choice.
Metolius Open Loop Sling Review
Compare prices at 3 resellers Pros: Relatively easy to untie weighted knots, comes in large selection of widths and lengths, affordable
Cons: Bulky for 11mm, not the best friction for alpine quickdraws, not as smooth as others
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Our Analysis and Test Results
Compared to the competition, the Metolius Open Loop Sling is relatively average, which still means that it is a good sling, worth buying and owning. However, the only area that it shows exceptional performance is in our knot test, in which we compared how easy it is to untie figure-eight knots once they have been weighted and tightened. We don't want to suggest that it is simply as easy as can be to untie these knots in this sling, as anyone who has hung on a knotted sling at a hanging belay for an hour can attest, but we found it to be far easier than most of the competition. This seems to be due to the relative thickness of the flat sewn sling compared to its width. It also comes in a variety of widths — 11mm, 13mm, or 18mm — and the largest selection of different lengths to choose from. This allows one to purchase exactly the lengths you need in order to equalize anchors as you like. The 120cm length that we tested is perfect for double bolt belays with a figure-eight knot to serve as the master point, but a 240cm length would be ideal for equalizing three traditional pieces that may be located in two different crack systems.
We compared this sling extensively to the BlueWater Titan Runner, which is another sling that uses both Dyneema and Nylon in its construction. The Open Loop Sling, like many other Dyneema slings, is made primarily with Dyneema in the middle as the load bearing part of the sling, but with a larger than average amount of Nylon on the edges to provide elasticity and color. The Titan Runner, on the other hand, integrates the two types of fibers, interweaving them together. This way of weaving the fibers likely does a better job of combining the positive attributes of both fibers (strength and elasticity), but as a much thicker, wider, and heavier sling, that was harder to untie knots in, we think that the Titan Runner simply isn't as easy or enjoyable to use, and is therefore not as ideal a choice as the Open Loop Sling for anchor building.
In previous reviews we referred to this sling as it used to be known, the Monster Sling. You may still encounter this name in other locations on the internet. This sling is made of Metolius's Monster Sling material, but is now called the Open Loop Sling, and remains relatively unchanged from previous versions.
The Metolius Open Loop Sling is made of a blend between Dyneema and Nylon fibers, with the white Dyneema fibers in the middle, and the green Nylon fibers woven around the edges. It is a flat sewn sling that nevertheless is a bit thicker, and slightly ovular in shape, compared to the Camp USA 11mm Express Dyneema Sling.
In the hand it is smooth and soft to the touch, but not as much as the strictly Nylon slings such as the Black Diamond Nylon Sewn Runner. The edges of this flat sling are ever so slightly abrasive, as we have found on many of the other flat sewn slings, although this complaint is very minor. The bar tacking, however, is larger profile and has two tabs of extra sling material hanging off each end, allowing for easier hang up on carabiners than the Mammut Contact Sling, which effectively negates this feature.
This sling excelled in our knot test, the main reason why we recommend it as the best choice for equalizing anchors. At 11mm wide it is not as skinny or as wide as the slings that we found to weld the tightest when knots are weighted. It is rather square cut, which actually makes it ever so slightly harder to tie knots in without twists (we found that twists in the knots don't compromise their ability to stay tied), but which allows it to not tighten as much, and thus be far easier to untie.
The only other sling that scored equal to it in this test had virtually the same attributes — the Camp USA 11mm Express Dyneema Sling. Both of these are easy to untie, regardless of whether the knot is a figure-eight or a clove hitch.
Alpine Quickdraw Test
The slings that performed the best at our Alpine Quickdraw Test were the ones that are thinner and less bulky than all of the others, so that the least amount of friction between different loops of the sling or the carabiner make it easier to equalize the sling to the proper length. Like the Camp USA Express Sling, which had very similar attributes, the Open Loop Sling scored in the middle of the field.
The large tabs on the bar tack also lowered the score a bit for this sling, because those tabs are more likely to hang up as they pass over and through a carabiner, regardless of whether tripling up the draw or extending it.
For this review, we tested the 120cm (47") version of this sling, and found it to be 47g, only 2g heavier than advertised on Metolius' website. By comparison, the 48" version of the BlueWater Titan Runner weighed in at 65g, a considerable amount more.
For comparison to the other double-length slings in this review, however, we are forced to rely on what Metolius advertises as the weight of their double-length (60cm) sling, which is 22g. This is competitively light with the Sterling Dyneema Sling, although just a few grams heavier than the lightest slings in this review, such as the Petzl Pur'Anneau Sling.
The 11mm width of this sling makes it one of the wider Dyneema slings, as a large amount of these types are either 10mm or even skinnier. That said, it is still considerably thinner than either of the Nylon slings that we tested.
Compared to the other two slings that are also 11mm wide, it is basically the same shape as the Camp USA 11mm Express Dyneema Sling, but is a fair bit thicker than the Trango Low Bulk 11 Sling, which we awarded a higher score.
We feel that the best application for this sling is for equalizing pieces of protection at anchors. Its blend of Dyneema and Nylon fibers, combined with a shape that allows one to tie knots, weight them, and then still untie them with relative ease, makes this an ideal choice for that purpose. Purchased in a 24" length, it performs just fine for extending protection pieces on lead, although wouldn't be out top choice for that purpose.
For the 120cm version expect to pay around $13 retail, or around $8 retail for a 60cm sling. This is an excellent price for a Dyneema sling, ranking as the most affordable for this type of fiber in this review. Since we recommend it as one of our top picks, we think this presents awesome value.
The Metolius Open Loop Sling is our Top Pick for Anchor Building, and is also an economical choice for use as a traditional lead sling in the double-length as well. Its blend of fibers, many length and width choices, and ease of untying knots all set it apart from its competitors, and are all reasons why we choose to recommend it.
— Andy Wellman