It is generally agreed that a heavy putter is more effective on slow greens, such as the Bermuda grass of the South, and that a light one is better on the fast bent-grass greens often encountered in the North. Unfortunately, this theory has led a great many golfers who play a variety of courses to conclude that they should carry both a light and a heavy putter and switch according to the speed of the greens. This is something I advise against. It is difficult enough to adjust to an unfamiliar putting surface without also having to adjust to a change in putters as well. When I first joined the pro tour I used the light blade putter that I had found so effective on the bent-grass greens of the kind of courses that most major amateur tournaments are played on. But it was out of my bag for good after five weeks because it seemed that no two courses on the pro tour had putting surfaces of the same speed. I made a successful switch to a blade putter that is built up to medium weight by having a thick flange on the back of the head, and that is the only putter I use. By all means use a light putter if you play only fast greens and a heavy-headed one if you consistently play on slow greens. But if you are a golfer who travels a lot and you like to play on many different types of courses, I suggest you find yourself a medium-weight putter and stick with it.