Cheapest I could find on the web.
The PXC 250 is a pair of closed, dynamic, supra-aural stereo mini headphones with NoiseGard? active noise compensation. Due to their active and passive attenuation of ambient noise, they let you enjoy music even in noisy environments. The headphones are foldable and come with a convenient belt pouch, making them an ideal travel companion.
Features of the Sennheiser PXC 250 include:
Dynamic stereo mini headphones
Great for travel and outdoor use with mobile sources such as CD, MD or MP3 players
Fold and flip: registered design allows the ear cups to be turned through 90° and fold the headphones closed (headphones will lock in open and closed positions)
For transport: supplied with soft belt pouch with extra pocket (185 x 105 x 40 mm)
1.8 m Kevlar-reinforced OFC copper cable with 3.5 mm jack plug, delivered with an adaptor to 6.3 mm (1/4") stereo and 3.5 mm double mono (for airline audio)
Ideal for use in coaches, trains etc.: soft ring ear pads with improved fit and closed ear cups ensure excellent passive attenuation of ambient noise (15 to 25 dB for frequencies above 1,200 Hz)
Ideal for aircraft and other environments with engine noise: the switchable NoiseGard active noise compensation attenuates frequencies below 1,000 Hz by up to 15 dB
Impedance optimised for use in aircraft
In-line NoiseGard power supply box (2 AAA size batteries) clips to the belt and can be rotated through 360°
For all types of modern music: detailed sound reproduction with a slight emphasis on the bass
High-resolution sound due to Sennheiser "Duofol" diaphragms with spiral embossing (reduces and spreads eigenforms)
Ultra-lightweight voice coils for high efficiency with portable players
Adaptive baffle damping (patent pending)
Bass tube for powerful, punchy bass
Lightweight: only 65 g without cable
Rugged and durable: robust steel headband with metal joints, steel-reinforced headband ends, connection to the ear cups tested for durability
I have a pair and would highly recommend - excellent for long haul flights.