The present invention discloses a bat having an interchangeable handle portion and barrel portion. The system involves electronic cards, commonly known as smart cards, and their equivalent computer software package. 5, wherein f1 is a focal length of the first lens, f is a total focal length of all the lenses, f3 is a focal length of the third lens, to is a lens thickness on an effective diameter of a rear surface of the third lens, and tc is a center thickness of the third lens.