With all the latest advances in digital music and sound fidelity, should you be using those headphones that came with your portable MP3 or CD player? Here's a way to get the best possible sound - The Sennheiser Way. The Sennheiser PXC 250 is a closed, dynamic, supra-aural mini stereo headphone with NoiseGard active noise compensation (requires 2 AAA batteries). 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.