The AKG K840KL wireless headphones are iPhone compatible, with an extended battery life up to two weeks. These AKG headphones offer you an expansive frequency range of 2.4 GHz for an outstanding voice quality and clarity. The AKG K840KL wireless headphones are extremely lightweight and give you long listening sessions. It is a pair of beautifully crafted wireless headphones that stream uncompressed 16-bit stereo audio.