Callaway X-12 irons are among the most popular in Hong Kong with about 1,000 sets having been sold since their introduction in January. Danny Ho, general manager of Sportsmark Trading, distributor of Callaway in Hong Kong, said he could sell another 1,000 sets if he could get them. Callaway has sold more than 250,000 sets of the irons that feature stainless steel heads and graphite shafts and has acknowledged it cannot meet demand. The line also comes with a steel shaft (Memphis 10 '98). The X-12 irons, which sell for $800 each, are thinner and more rounded than the Big Bertha line and have been designed to perform like the more expensive Great Big Bertha tungsten titanium irons. Callaway claimed the challenge in making the club had been to achieve a centre of gravity which was low and far enough behind the club face for maximum for giveness and to help players get the ball airborne more easily. Fred Port, president of Callaway Golf International, said sales of the X-12 irons had been 'overwhelming' and their popularity had played a large part in dismissing the notion that the company produced only drivers and woods. 'In general, Callaway is number one in the world market. People may think Callaway is a wood company but the single largest-selling iron in the world is the XL. No other iron is even close to it,' he said. 'The reality is Callaway is rapidly becoming the number one iron company in terms of volume and units.' In Hong Kong, Callaway sells 800 to 1,000 drivers a month in its Big Bertha War Bird ($1,450), Biggest Big Bertha ($2,950) and Great Big Bertha ($3,350) lines. Last year, Callaway Golf reported sales of US$842.9 million, a 24 per cent increase year on year.