The Cobra BiO Cell irons feature a perimeter undercut cavity design and tungsten weights strategically positioned to produce a combination of forgiveness and explosive distance. They feature BiO Cell technology which re-distributes weight from the face and body to increase perimeter weighting and positions the center of gravity directly behind the sweet spot. This iron features Cobra’s largest unsupported face ever to create incredible face flex delivering increased ball speeds and maximum distance. E9 Face Technology and metalwood face-weld construction combine to create a higher COR for increased distance and forgiveness. The long irons (3 through the 7 iron) feature a hyper 17-4 stainless steel construction with heel - toe tungsten weighting for incredible forgiveness, while the short irons (8 iron and shorter) have a 431 stainless steel construction with tungsten weighting centered behind the hitting area for added distance.