Callaway Golf Men's X2 Hot Pro 7 Piece Irons Set (Set of 7 Total Clubs: 4-PW, Right Hand, Steel, Stiff Flex) Thinner Hot Face: We made X2 Hot Pro Irons longer than ever, The thinner hot face creates a larger sweet spot Central Mass Bar: Higher MOI and enhanced feel; That was the goal behind concentrating this mass bar low and central in the head Progressive Offset: Less offset in the short irons for more precision and shot control