Imperial Combination Wrench for Working at Height Secure Tools have a large collection of imperial combination wrenches for working at height safely. Available in a large range of sizes, the combination of both an open-ended and box-ended wrench delivers the perfect tool to unfasten a variety of nuts and bolts and separate them at speed. Their strong, chrome-plated build is corrosion-resistant and easy to clean, providing incredible durability that can stand up to a lifetime of arduous working conditions. While each imperial combination wrench includes a tough open ring attachment point to tether the item to a harness or belt and stop tool droppages occurring when working from height.