In the words of Line 6:

For guitarists and bassists who want professional-grade HX modeling technology in an ultra-compact pedal, the HX Stomp guitar processor offers more than 300 Helix amps, cabs, and effects in a stompbox-sized design that fits easily in the pocket of a gig bag. Whether you prefer to play through a traditional amp-and-pedal setup, or go direct onstage or in the studio, HX Stomp is at once a super stompbox, the ideal backup or travel rig, an add-on tone expander when combined with other modelers, and even a multi-channel audio interface.