Is it really possible - a narrow sole design can be forgiving? In a word, yes! The slimmer profile of the Acer XK irons was designed based on feedback over many years from golfers who just didn't want a "clunky" appearance when looking at the irons from 'address' position. However, these very same golfers still wanted all the modern game improvement features that made possible today. The XK irons fit the bill! They also have a non-glare topline and modern offsets that allow the non-pro golfers to hit solid and straight shots. This design could soon be the standard in the custom clubs industry. 431 stainless steel. Really nice!