The 4" long extension allows you to reach areas that would otherwise be inaccessible with a standard die grinder. This is particularly useful for deep or hard-to-reach spots in automotive, industrial, and construction applications. It enables you to work in tight spaces and around obstacles, making it easier to perform tasks in confined or awkward locations. The longer extension provides better leverage, allowing for more controlled and precise work. This can be especially important when working on detailed or delicate tasks. The added length helps to stabilize the tool, reducing the risk of slipping or making errors, which is crucial for achieving high-quality finishes. By allowing you to maintain a safe distance from the workpiece, the extension reduces the risk of injury from flying debris or accidental contact with the cutting tool. It can help reduce strain on your hands and arms by allowing you to work in a more comfortable position, which is especially beneficial during extended use.