Sony MDR-NC20

Reduces Noise by 70% (10dB) when noise canceling circuit is switched on
Ideal For Travel gives you peace and quiet on planes, trains, buses and cars; quiets noisy air conditioners
Ideal For Outdoor Use when gardening or on a noisy street
Noise Canceling Circuit actually senses outside noise with built-in microphones and sends an equal-but-opposite canceling signal to the headphones; cancels noise from 50Hz to 1,000Hz, with a maximum of 10dB noise cancellation in the critical range from 100 to 400 Hz --where the human ear is super-sensitive
Noise Canceling On/Off Switch with red Power LED to indicate when Noise Canceling is operating; when Noise Canceling is off, headphones continue to function for music listening
Closed Headphone Design for even greater isolation from outside sound
30mm Diameter Driver delivers deep bass all the way down to 16 Hz; provides outstanding dynamic range
Neodymium Magnet for maximum energy in minimum size; ounce for ounce, Neodymium is far more powerful than conventional Samarium Cobalt or Aluminum magnets
Folding Headband and pivoting earpads make for easy storage in a backpack, briefcase or purse
Extended Battery Life approximately 45 hours with a single AAA alkaline battery
Detachable Input Cord to connect an audio source and listen to music
Gold-Plated Mini-Plug to connect an audio source; provides exceptional corrosion resistance, superb conductivity, low noise
Type: Closed, Dynamic (with Noise Cancellation)

Driver Unit: 30mm

Magnet: Neodymium
Headband: Folding type
Power Source: "AAA" x 1 Battery
Battery Life: Approx. 45 hours (alkaline)
Approx. 23 hours (manganese)
Power Switch: Manual
Noise Reduction: >10dB at 300Hz
Impedance: NC Power On: 24 ohms
NC Power Off: 56 ohms

Sensitivity: NC Power On: 99dB/mW
NC Power Off: 98dB/mW
Power Handling Capacity: 100mW

Frequency Response: NC Power On: 16 - 22,000Hz
Cord and Plug: 1.5 ft (0.5m) cord with gold-plated micro plug;
Separate 3.3ft (1m) cord gold-plated stereo micro jack to gold-plated, L-shaped stereo mini-plug