Bridgestone J15 Muscle Back Individual Iron The Bridgestone J15 Muscle Back (J15MB) Irons are design for low to no handicap golfers. Being forged from premium carbon steel gives these irons a great feel. The J15MB Irons feature an ultra compact head for the ultimate shot shaping and versatility. The J15MB Irons also have a narrow Sure Contact Sole; Bridgestone? smallest sole, for consistent contact and turf interaction demanded by the best players in the game. IronLoftLieLengthSwing WeightOffset (mm)Bounce321?60.5?39.0D32.53.0?423.5?61.0?38.5D32.53.0?527?61.5?38.0D32.03.0?631?62.0?37.5D32.04.0?735?62.5?37.0D32.04.0?839?63.0?36.5D31.55.0?943?63.5?36.0D31.56.0?PW47?64.0?35.75D41.57.0? Products Code:BGS0173 Products Name:Bridgestone J15 Muscle Back Individual Iron.