Koss developed the KDE250 with a pair of dynamic transducers that mount at a perpendicular angle. The larger 20mm transducer is low frequency dominant and ported while the 13mm transducer focuses on mid and upper frequencies in a side firing angle. This combination of transducers allows greater efficiency and accuracy across the entire musical spectrum to levels that exceed audibility. Ideal for gamers who enjoy deep bass, the SB40 features a dynamic element for premium sound at all volume levels. Incorporating a frequency response of 20-20,000Hz, the SB40 delivers a full-range of sound that will bring your favorite games to life. Whether you're alone or online, the SB40's sound will be so efficient that you'll hear your opponent before they even know you're there. Its large, closed ear cups surround the ear for maximum isolation so you can stay focused on saving the world or kicking a forty-yard field goal. Soft, leatherette ear cushions envelope your ears without creating pressure for long lasting comfort. The microphone eliminates excessive background noise for a greater ease of use with PC voice applications, such as speech recognition. The SB40 has an adjustable headband to fit most head sizes. Built of durable plastic, the SB40's headband can stand up to the rigors of daily wear and tear for a fits-like-new feel after years of use. Built to last, the SB40 is covered under Koss' Limited Lifetime Warranty - the only warranty of its kind in the stereophone industry.