ST-X Driver Ultra-stable with high draw bias A draw-biased carbon composite construction aided by a heel side sole weight. Built upon the 2nd generation of Mizuno's Forged SAT2041 Beta Ti face – for potent ball speeds and consistent performance over time. Slower swing speeds will benefit from the J-Spec – incorporating an incredibly lightweight 39g MFusion graphite shaft. "In testing, a lot of our tour players preferred the ST-X over the ST-Z for its deeper shape and slightly smaller profile. I'd recommend starting with an open mind and dropping the ST-X alongside the ST-Z in the address position. For a draw bias driver, it's not going to be what most players expect." -CHRIS VOSHALL Highly resilient Forged SAT2041 Beta Ti Face As a high strength Beta Ti, SAT2041 maintains its characteristics and resists micro fractures for longer than the commonly used 6-4 Ti. New Multi-thickness CORTECH Face Refined to maximize the return from Mizuno's Beta Ti face. Ball speeds most noticeably improved low on the clubface. 'Dense' or solid feedback The majority of Mizuno's tour players expressed a preference for more dense feedback through impact. Mizuno's engineers spent a year finessing the sound to a more muted, powerful tone. Quick Switch Adjustability 4 degrees of loft adjustability to fine-tune look and trajectory. Optimized Wave Sole Plate Delivers an additional contribution to ball speed – especially low from the clubface. X-Axis design for draw bias Expanded toe located carbon composite window, with heel located sole weight combine to produce a reliable draw bias. More compact profile Slightly deeper back portion and more upright visual lie angle.