The Shure KSE1200SYS Analog Electrostatic Earphone System is a premium choice for music lovers on the move. It's perfect for use with portable media players. The system includes a pair of single-driver electrostatic earphones and a matched high voltage amplifier. The earphones are lightweight, with an ergonomic shape that minimizes ear fatigue, and come with comfortable sound isolating sleeves that block up to 37 dB of ambient noise. The amplifier is housed in a black anodized aluminum case. The system has a rechargeable Li-Ion battery that provides up to 12 hours of playtime and can be charged via USB from a standard wall charger or computer. The earphone cable is custom-designed to isolate each conductor. The system is easy to integrate with premium audio players. The earphones have a frequency response of 10 Hz to 50 kHz, a maximum SPL of 113 dB SPL at 1 kHz and 3% THD, and weigh 44.0 g (1.55 oz.). The amplifier has a signal-to-noise ratio of up to 107 dB A-weighted, an adjustable gain range of -40 dB to +60 dB, and weighs 155.0 g (5.47 oz.). It measures 93 × 53 × 21 mm H × W × D.