Metric Combination Wrench for Working at Height Secure Tools have a large collection of metric combination wrenches for working at height safely. Available in metric measurements ranging from 6mm to 50mm, the combination of both an open-ended and box-ended wrench makes it the ideal tool to unfasten a variety of nuts and bolts and separate them at speed. Their solid, chrome-plated build is corrosion-resistant and easy to clean, delivering exceptional durability that can withstand a lifetime of arduous working conditions. While each combination wrench includes a sturdy open ring attachment point to tether the item to a harness or belt and prevent tool droppages when working from height