Nippon Shaft is a subsidiary of NHK, a Yokohama, Japan-based manufacturer of steel engine valve springs used in automobiles. Such springs must be both pliable and durable over the course of 100,000 miles. That same principle is at work when Nippon Shaft makes lightweight shafts for golf clubs. The real â€œmagicâ€ of Nippon Shaft sub-100-gram steel shaft is its ability to be both â€œsoftâ€ and â€œhardâ€ at the same time. In addition, all Nippon Shaft steel shafts are â€œconstant weightedâ€. Read more.