This traditional pear-shaped head with deep face is the winningest driver on the PGA Tour. The unique hosel and shaft that bores through the head create a stiff internal tube that stabilizes the head impact. This maximizes energy transfer to the ball for faster exit speed. The variable wall thickness and internal weight properties create flat, hard ball flight, which better players prefer. Contrasted from Callaway, for example, the center of gravity in the 975D is forward and higher in the head