Product attributes material: premium flex plus carbon steel ergonomic, durable two-component handle This is a combination of a 1671.1 wrench, a screw with a nut and a handle. The double threaded bolt allows this wrench to be used with standard Shimano bottom bracket cartridges as well as Shimano Octalink and Truvativ. How to use the device: Advantages: To remove the bottom bracket, insert the wrench into the bottom bracket nut. The screw locks the entire assembly onto a single axis, preventing the wrench from slipping and damaging the bottom bracket nut. The 350mm handle with an ergonomic grip made of two types of material makes work easier. A similar procedure is used for assembly. The 24mm nut is tightened with a 24mm wrench, and the tightening torque is checked with a torque wrench.