The secret of the FireSole is titanium that also features tungsten and a low center of gravity.
Features
Titanium's light weight allows a traditional head shape that gives you greater forgiveness, confidence and performance. The tungsten goes where it can have the biggest impact: directly behind the sweetspot, in the form of a center-oriented high-density sole weight plug. The ideally-located low center of gravity also reduces backspin and produces the proper launch angle for the penetrating trajectory you're looking for. And that means a noticeable increase in distance. Headcover included.