AKG K 420 Foldable Mini Headphone - Blue (Discontinued by Manufacturer) AKG Foldable Mini Headphone - Blue. Connectivity Technology: Wired Foldable Mini Headphone - Blue AKG K 420 Headphone - Blue Lightweight, on-ear design is comfortable enough for everyday use iPhone compatability allows use with an iPhone without the need for an extra adapter. High-performance, ultralinear sound is free of distortion, even at high volume levels, making it perfect for listening to today's music and movies Unique 3D-Axis folding design allows the K420's cushioned headbad to collapse along a three dimensional axis to fit easily into the carrying pouch