The KTM 690 Duke is the latest generation in KTM's line of midrange single-cylinder engine supermoto or naked motorcycles that began with the 1994 609 cc (37.2 cu in) displacement Duke 620 or Duke I, followed by the 1998 625 cc (38.1 cu in) Duke 640 or Duke II, followed by the 654 cc (39.9 cu in) Duke III, and finally the 690 cc (42 cu in) Duke IV made since 2012. Both the Duke III and Duke IV are called the 690 Duke.