The inner cavity design is not new to Miura. Is was first used with their hugely popular IC 2003. (IC 6001 in Japan). Modern technological advances have allowed the Miura’s to improve on the original while optimizing ball speed and performance. This is accomplished by integrating a face of 455 Carpenter Steel (as found in our PP 9005 G) and use of the Hayate variable weighting system which allows for customization by your Miura dealer. With the standard 8g weight included, the 244g weight of the 23° ICL Utility Iron head is exactly the same weight as a standard 4iron.