From Golf Magazine (Buyer's Guide, May 2009)
It's for: All skill levels
Josh Breier, Principal Design Lead Engineer: "We developed a new outer head shape and internal geometry for 'hotter 9-point' performance. Each model has a distinct center-of-gravity location to provide optimum ball-flight conditions for all player types and ball speeds. We also adjusted face geometry to maximize efficiency and ball speed across the face. Longer length [45.5'] and lighter overall weight [by 6 grams] mean higher ball speeds for all player types."
How it works: The new stick is shorter from face to rear than Speed LD, narrower from heel to toe and has a more rounded topline and leading edge. This profile (5 percent less overall surface area) delivers a bigger hitting area while freeing up more weight than in the Speed LD. As a result, the S9-1 is more stable (higher MOI) and has a hotter face (faster ball speed). A dual-rhombus pattern behind the clubface is used to shore up ball speed on off-center contact.
Each S9-1 model (Pro, F, M, M Offset) has specific internal weighting and matching shaft to max-out ball speed for targeted player types. For example, the center of gravity gets more draw-biased as you graduate from S9-1 Pro to S9-1 M Offset. S9-1 Pro D and S9-1 Pro S (light composite crown and a swingweight screw in the sole) are built for guys with 150+ mph ball speeds who benefit from high launch, low spin and added workability. Most golfers, however, require the S9-1 F (125-155 mph ball speed) or S9-1 M (