The AP3 head is hollow with a thin face. This allows for a higher initial ball speed, and the overall moment of inertia of the head is increased, making the head more stable. The "AP3 iron" is both forgiving and allows the ball to travel further. I think it's an iron recommended for intermediate to advanced players! - Brand: Titleist - Model: 718 AP3 - Shaft: NS Pro 950GH - Club Numbers: 5I〜PW - Year of Purchase: 2018 (New) Thank you for viewing. This is a used item, but it has been stored without use during my overseas assignment, so it is in good condition. Thank you for your consideration. (I will respond flexibly to the price, so feel free to comment)