The XtendAlign was developed to be a personal and portable version of Klaas Kwakkel's original Targaline Putting Aid.
Features a mirrored base and retractable cord that extends to a plastic cup. The post that inserts into the cup may be removed and stuck into the green independently of the cup for practicing breaking putts. Note: When you get your product you will need to fill the base with a little sand so it doesn't slide when the string is extended.
When standing over the putting string the player can glance back toward the mirrored base. If they see 1 string only, the eyes are directly over the string. Most putting experts agree that the eyes should be behind the ball but along the target line. Some players have their eyes slightly inside the line and with the XtendAlign you can monitor this too. The product is small enough to slip inside your golf bag and may be used both indoors and outdoors.