Mizuno ST-Z 230, ST-X 230, ST-X PLTNM 230 drivers

Each ST-230 driver has a thin Forged SAT 2041 Beta Ti face. (David Dusek/Golfweek)

The ST-Z 230, ST-X 230 and ST-X PLTNM 230 all have carbon fiber crowns that weigh about 12 grams, saving weight on the top of the club, along with carbon fiber panels in the sole. They also have been made with very thin Forged SAT 2041 Beta Ti faces designed to flex efficiently at impact. 

The ST-Z, ST-X 230 and ST-X PLTNM drivers also each have an adjustable hosel that allows players and fitters to increase or decrease the loft by as many as 2 degrees. 

The blue TPU material has stainless steel in it to lower the center of gravity. (David Dusek/Golfweek)

What sets the ST-230 drivers apart from their predecessors is the addition of a CorTech Chamber. Mizuno used to add a Wave Sole behind the leading edge of its drivers to allow the lower portion of the hitting area to flex more and broaden the sweet spot, and the new CorTech Chamber takes things a step further. It is a channel cut into the sole of each driver that is filled with a special blue thermoplastic polyurethane that has stainless steel in it.

The cut-through design lets the lower portion of the hitting area flex more efficiently, but the steel floating in the TPU weighs more than the titanium it replaces. So it works with the carbon fiber top to drive down the center of gravity and pull it forward. Mizuno engineers learned that a low and forward center of gravity helps reduce spin and increase ball speed, so the CorTech Chamber’s effect should be increased distance with a more solid feel.

The CorTech Chamber does such a good job of allowing the lower part of the face to flex that it reduces strain on the seam where the hitting area and sole meet, allowing Mizuno to make the lower part of the face even thinner. The company also made the three internal ribs that help improve the sound of impact smaller and lighter. 

Mizuno ST-Z 230 driver (David Dusek/Golfweek)

The ST-Z 230 driver was designed with the center of gravity on what engineers call the z-axis, which is the center line of the head. Doing this creates a neutral weight distribution that can help golfers who like to hit draws and fades shape shots more easily.

The ST-Z 230 has a glossy black crown with carbon fiber weaving. (David Dusek/Golfweek)

The ST-Z 230 also has a 14-gram weight in the back of the head to boost the moment of inertia and increase stability. 

Mizuno ST-X 230 driver (David Dusek/Golfweek)

The ST-X 230 driver also has a 14-gram weight in the back, but it is positioned slightly toward the heel side, and its carbon fiber sole goes less deeply into the heel area than the ST-Z’s composite sole. This creates a draw bias to go along with the stability.

Compared to the ST-Z 230, it is slightly larger front to back in the address position.

Mizuno ST-X PLTNM 230 (Mizuno)

ST-X PLTNM 230 was designed for slower-swinging golfers who want a lightweight option to create more clubhead speed. It has all the technologies found in the ST-Z and ST-X, like the Forged SAT 2041 Beta Ti face, carbon fiber crown and sole panel, and the CorTech Chamber, but it has a 7-gram weight in the back. It is about 45.75 inches in length (instead of 45 inches) and comes standard with a lighter shaft and grip.