to retail dealers and expanded its product line through acquisitions. C. G. Conn founded the Continental Music retail subsidiary in 1923 which, at the height of its success, included a chain of over 30 music stores. During the 1920s C. G. Conn owned the Elkhart Band Instrument Company (1923–27), the Leedy Company (1929–55), a manufacturer of percussion, and 49.9% of the stock of the retailer H. & A. Selmer (1923–27). Conn purchased the drum manufacturer Ludwig and Ludwig, the instrument import/retail operation of the Carl Fischer company, and accordion manufacturer Soprani in 1929. From 1940 to 1950 the company owned the Haddorff Piano Company, and from 1941 to 1942 the Straube Piano Company. Greenleaf expanded and upgraded C. G. Conn's plant to increase production and developed new lines of wind instruments to sell. By 1917, using a new hydraulic expansion process which Greenleaf introduced to the plant, the assembly-line work force had increased to 550 employees who were turning out about 2500 instruments a month. In 1917 C. G. Conn introduced the Pan American brand for its second-line instruments, forming the Pan American Band Instrument Company subsidiary in 1919 and moving production of second-line instruments to the old Angledile Scale factory later that year. In 1930 the Pan American company was absorbed by C. G. Conn, with C. G. Conn retaining and utilizing the Pan American brand for its second-line instruments until 1955. By 1920 C. G. Conn was producing a complete line of saxophones. In this area they had stiff competition from other big saxophone makers such as Buescher and Martin. Around 1917 C.G. Conn introduced drawn tone holes (after a patent by W.S. Haynes in 1914) eliminating the necessity of soft-soldering tone hole platforms onto the bodies of the instruments. Around 1920 C. G. Conn introduced rolled tone hole rims, a feature that enhanced the seal of the pads and extended pad life. Rolled tone holes remained a feature of Conn saxophones until 1947. By the late 1920s the success of Conn's latest "New Wonder" model saxophones with dance orchestras was gaining widespread attention, leading European manufacturers to produce horns closer to the deeper, richer, bolder "American" sound. Selmer (Paris) introduced the American-sounding "New Largebore" model in 1929 and the new Julius Keilwerth Company in Czechoslovakia produced saxophones influenced by the C. G. Conn design, including rolled tone holes and microtuners. As sax sales plateaued in 1928, Conn