(Continued from above) Throughout most of the history of the company, Akro Agate was the largest manufacturer of marbles in the United States.  The company introduced a number or improvements and design changes to its machinery, which yielded several different types of marbles that could not be replicated by competitors. Many Akro Agate marbles are very collectible today. The company produced both single-stream and variegated stream marbles, in all types except ribboned and veneered.