The company's first series of pocket watches, the Broadway Limited, was marketed as the "Watch of Railroad Accuracy," and Hamilton became popular by making accurate railroad watches. Hamilton introduced its first wristwatch in 1917, designed to appeal to men entering World War I and containing the 0-sized 17-jewel 983 movement originally designed for women's pendent watches. In 1928 Hamilton purchased the Illinois Watch Company for in excess of $5 million from the heirs of John Whitfield Bunn and Jacob Bunn. Some of the most collectible early Hamilton wristwatches include The Oval, The Tonneau, The Rectangular, The Square Enamel, The Coronado, The Piping Rock, The Spur, The Glendale, The Pinehurst, The Langley, The Byrd, The Cambridge, the Barrel "B", and The Flintridge. Many models came in both solid gold and gold-filled cases and, though rare, some wristwatches such as the Grant were made of silver.