Product Overview: Superior Distance - World's first patented dual power core with Bismuth metal provides greater explosiveness. Unlike normal metal, Bismuth expands 3.5% in volume, leading to greater energy transfer. Features: Superior Feel and Durability - Optimized spin rates by Urethane cover with a unique coating process for greater durability provides improved spin control and the ultimate soft feel at impact Superior Technology - With advanced world-leading technology, the White Colour S4 provides superior performance characteristics proven by some of the world's best tour professionals and extensive Iron Byron testing and flight monitor data