New advances in materials and design have served to expand the performance of Koss products. The company's product development team and engineers look for the most innovative combinations of existing and new technologies to deliver the most exciting products possible.A portable headphone is a headphone that is used on-the-go. Portable headphones tend to be smaller, more lightweight, and may have features that lend themselves to listening on-the-go, like carrying cases or collapsible headbands.Koss KTX PRO1 features a titanium-layered diaphragm for accurate sound reproduction, foam ear cushions for an open, hear-through sound and an adjustable headband with a sling for a comfortable and secure fit.