Notch Rigging Thimbles were designed by arborists and built by engineers. They are purpose-built for the arboriculture industry, with improvements over the original marine products on the market. Splice them into a sling for use as a rigging point or redirect. Wider rope groove to accommodate more appropriate sizes and types of rope for various sling configurations. Bigger, gentler bend radius for running rope. Non-anodized aluminum for extended life. Interior diameter is specially sized in relation to the other Notch Rigging Thimbles for better retrieval and use with splices. Effectively unbreakable in standard configurations on our 25,000 lbs. horizontal proof test machine. Minimum breaking strength tested in the worst case configuration scenario - and clearly marked on every thimble. Tensile Strength: 10,000 lbs (44.4 kN). Lifetime wear guarantee - If at any point in time your rigging thimble shows a "groove" from normal use, send it back to us and we'll replace it for free. (Does not cover dents, scratches, or the cost of splicing).