The Mayhew 45052 SAE Twisted Hex Key Set, 9-Piece is made up of Superior Quality S2 Tool Steel. Twisted prior the heat treat to increase torque capacity. Longer shaft for added leverage. Exceeds ANSI standards. Color coated to resist corrosion, manganese-phosphate contact areas to resist wear. Made in the USA. Comes in a Display package. Comes with an unlimited lifetime warranty. Mayhew stands for quality, dependability, and confidence. When the caliber of the tools is just as important as the skills of the professionals employed, businesses trust Mayhew to get the job done. Since 1856, our punches, chisels, and pry bars have been the go-to tools for OEMs and professional mechanics throughout the country. And while our company has grown to meet the needs of the professional market, as well as those of the do-it-yourself automotive enthusiast, our focus has never changed-leveraging our strength to build your business.