The advantages of putter 10 (and 10a) are described as follows:

1. A person striking ball 12 would be able to accurately direct the ball 12 in a linear direction along a line, which is in a plane bisecting the contact surfaces 56, 58 of groove 54.

2. If a person does not preferably hit ball 12, and if ball 12 is within the contact surfaces 56, 58 of groove 54, then ball 12 will travel in the selected direction.

3. Groove 54 permits a correction to ball 12, when ball 12 is struck inaccurately.

4. Contact surfaces 56, 58 of groove 54 provide two equal contact forces on ball 12, and their equal transverse force components cancel out, so that their equal forward force components are additive and are directed in the line of travel of plate 26, whereby ball 12 moves in a desired linear direction.

5. A person can direct ball 12 to a cup on a putting green, by assuring that the projection of scribe line 38, which is coplanar with a line bisecting the contact surfaces 56, 58 of groove 54, is aligned with the center of the cup.

6. Putter 10 (10a) is ideal as a teaching tool.

7. Putter 10 (10a), which is shown as a right hand putter, can be made opposite hand as a left hand putter.

8. With putter 10 (10a), a more exacting muscle memory or coordination is developed, by a repetition of a more precise stroke, which involves a more accurate coordination of eye, hand ball and putter, than that of the prior art putter.