Topeak DuoHex Tool 6mm. The 6mm hex wrench is a staple in every home mechanic's tool box and Topeak has created a deluxe, super versatile version in their DuoHex Tool. This pro quality, chrome vanadium steel wrench features a pair of 6mm wrench options a traditional 6mm hex wrench at one end plus a 6mm ball at the other end for hard to reach and blind locations. Additionally, there's a padded, ergonomic handle that's easy on your hands during usage. The DuoHex 6mm tool is perfect for maintenance of cranksets, bottom brackets, and pedals.