Our hexagonal kellies are made from AISI 4145H modified alloy bars that are quenched and tempered full length. After such heat treatment, its brinell hardness can reach 285-341. Kelly's end, drive cross-section and joint are all processed and tested conform to API criterion.  

We are responsible for customers, strictly implement the standard specifications, and provide high-quality products and service. Sincerely hope to establish good trade relationship with all friends at home and abroad.