DMM Wallnuts are the foundation of a comprehensive climbing rack. They're made using different alloy for each size - smaller Wallnuts use a harder alloy to prevent shearing, while larger sizes are softer so they can bite into placements. They can be placed in two different orientations, allowing a single nut to cover a range of cracks, and they're tapered across both their face and sides, helping them sit better in cracks that are rarely parallel sided.The grooved faces reduce weight, help the nut seat better in cracks, improve security in shallow placements, and resist lifting out when a leader moves past them. Their wire is stiff enough to allow overhead placements, but flexible enough to reduce the chance of lifting out ... More info