In 1928 Conn opened its Experimental Laboratory, which was unique in the industry, under the direction of C.D.'s son Leland Burleigh Greenleaf (Wauseon, Ohio, 12 August 1904 – Leland, Michigan, 29 March 1978). Under his directorship, the department developed the first short-action piston valves (1934), and the 'Stroboconn' (1936), the first electronic visual tuning device. It also developed the "Vocabell" (1932), a bell with no rim, which Conn described as "vibrat freely and in sympathy with the vibrating column of air in the instrument," Conn also developed the "Coprion" bell (1934), a seamless copper bell formed by directly electroplating it onto a mandrel. Under Greenleaf's saxophone specialists Allen Loomis and Hugh Loney, Conn's research and development resulted in the designs of the 6M alto (1931), 10M tenor (1934), and 12M baritone (1930). The 12M baritone was the first saxophone with both bell keys on the right side, followed by the King Voll-True II (1932) and Selmer Balanced Action (1936). The 6M alto featured an innovative double socket neck that eliminated the large collar on the body tube at the neck joint for a more positive seal and even response, later adopted for King altos and tenors. From 1935 through 1943, Conn produced the 26M and 30M "Connqueror" alto and tenor saxophones, featuring screw-adjustable keywork and improved mechanisms for the left hand cluster. The keywork was the most fully adjustable of any saxophone during that period. Conn's laboratory was expanded into the Division of Research, Development and Design in 1940, directed by Earle Kent (b Adrian, Texas 22 May 1910; d Elkhart 12 January 1994). Conn's combined abilities in close-tolerance manufacturing and electronic devices made them a valuable resource for wartime production.