This is the Topeak Duohex 6mm. When it comes to tools, you need durability and comfort. Topeak have produced this pro quality, chrome vanadium steel 6mm hex wrench with one ball end for hard to reach and blind locations. Chrome vanadium is also used for large breaker bars, so you know this is one tough hex wrench. Ergo padded handle for increased grip and comfort while handling. Great tool for maintenance of cranksets, bottom brackets, and pedals. Stop struggling with the small allen key and put one of these in your tool kit.