After a long and challenge filled design process, we are happy to report that our latest design prototypes for the HEXtension passed stress testing with flying colors, holding 150 lb-ft of torque as measured on the torque wrench. We suspect that the force may even have spiked as high as 160 lb-ft, but the wrench only reads to 150, so we cannot say for certain. The design has proven robust, with only minimal fatiguing visible along the male end from when we seriously torqued on the tool. As long as you treat your HEXtension with respect and care, it'll do the same for you, remaining durable and long lasting. See below for a slideshow of the new prototypes, including the advances in design to relieve stress points and increase overall user friendliness. The prototype we tested was of 4130 steel; we will be conducting testing with a 4140 unit next week, and then we will make our final decision for production. Again, we want to express how grateful we are to the patience shown by everyone as we work to bring to market a tool that will last for years to come.