Great for travel & outdoor use with mobile sources such as CD MD or MP3 players Ideal for aircraft & other environments with engine noise the switchable Noise Gardand 153 active noise compensation attenuates frequencies below 1000 Hz by up to -15d B Impedance optimised for use in aircraft Ideal for use in coaches trains etc soft ring ear pads with enhanced fit & closed ear cups ensure excellent passive attenuation of ambient noise -15 to -25d B for frequencies above 1200 Hz Fold & flip design allows the ear cups to be turned through 90anddegree & fold the headphones closed High-resolution sound due to Duofol diaphragms with spiral embossing reduces & spreads eigenforms Adaptive baffle damping Bass tube for powerful punchy bass Robust steel headband with metal joints steel-reinforced headband ends connection to the ear cups tested for durability 2-year guarantee The PXC 250 are a pair of closed dynamic super-aural stereo mini headphones with Noise Gardand 153 active noise compensation. Due to their active & passive attenuation of ambient noise they let you enjoy music even in noisy environments. The headphones are foldable & come with a convenient belt pouch making them an ideal travel companion.