-BiO CELL Irons are packed with game changing technology.- The long and mid irons feature heavy tungsten weights strategically positioned in the heel and toe for more forgiveness, while the short irons have the tungsten positioned directly behind the hitting area for a solid feel, optimal spin control, and versatility as you approach the green. The irons also feature Cobra’s largest unsupported face ever to create more face flex at impact for increased ball speed and maximum distance. And of course we’ve gone the distance - the BiO CELL Irons are offered in four colors providing personalization and choice with tungsten-fueled performance.