The DDJ-FLX10 is a 4-channel performance DJ controller for rekordbox and Serato DJ Pro. It includes a host of brand-new features including STEMS technology, which enables new creative possibilities such as the easy performance of mash-ups on the fly with no need to prepare tracks in advance.Load the regular songs from your music library and create remixes and mash-ups on the fly by independently manipulating the 3 key parts of the music: vocals, drums, and inst (other instruments including bass and synths). There are dedicated color-coded buttons to control each part, so you'll always have a clear visual grasp of what's playing.