EOS Ti-22

The EOS-Ti 22 was Yamaha's first commercial club to utilize the company's proprietary ultra-strong titanium alloy techniques to use forged materials in wood clubs—a difficult task when a hollow construction is called for.
These allows are approximately 1.6 times stronger than conventional forged titanium, allowing the thickness to be reduced to create a 213 cc metal headed wood club—the largest volume metal-headed wood in the world (at the time), without altering the weight.
This increased the area of the sweet spot by approximately 10% over clubs with a normal forged titanium head, allowing directionally stable driver shots with excellent flight.
The EOS Ti-22 won a Good Design Award in 1991.