Research shows that over 70% of all golfers incorrectly align their putts. Use of this device can greatly increase your accuracy and proficiency on the putting green. These units will work on most putters (10mm maximum shaft size) and project a red dot where you aim to more accurately define your putting line. They aren't as visible in bright sunlight, shaded areas or indoor practicing is more ideal for this type of item. When using on center shafted putters, you just have to compensate for the slightly different positioning of the putting line due to where they're mounted. These are perfect for anyone who wants to help improve their golf game, and works for both left and right handed golfers. These can retail for as high as $49 each, but buying in large quantities allows me to pass the savings on to my customers and offer them at a greatly discounted WHOLESALE price. I have these custom made directly from the manufacturer, so my prices and quality can't be touched. Don't settle for bulky outdated models at higher prices, get the smallest, best designed units around, which you'll find here at Genaldi.com!