Product Description Interchangeable Head Drives for Pre-Sets - Fixed Square Drive Heads.It belongs to the tools category.It is of durable quality and highly efficient. From the Manufacturer This CDI Torque 1-Inch drive fixed X head is for use with pre set torque wrenches, these heads are designed for use on productions lines and other applications where a specific torque is required for repetitive operations. The design, fabrication, and materials used have been developed in coordination with major manufacturers in actual production use. Match the shank size on the head with the shank size on the desired pre set torque wrench.