Devices with stereo speakers deliver sound from independent channels on both left and right sides, creating a richer sound and a better experience.
With a detachable cable you can use alternative cables, and if the cable is pulled it will pop out instead of breaking.
Folding devices are good for transporting as they take up less space in your bag.
The device comes with its own special case or pouch, which is useful for safe transportation.
An L-shaped plug is better if the jack is on the left or right side of the device, so that the cable isn't bent, and is less likely to break when the device is in your pocket.
The device sits tightly in place, creating an acoustic seal which reduces background noise and prevents your music from leaking out.
A standard 3.5mm male connector is suitable for use with all MP3 players and computer sound cards.