Sony MDR RF930K

The wireless design of these Sony headphones lets you move inside and outside your house and still enjoy music or TV sound tracks. It allows you turn the volume up late at night - without disturbing anyone else. 900 MHz radio frequency (RF) transmission is used in this system for better sound quality and greater range than earlier 40 MHz systems. The headphones have 130 feet transmission range for listening enjoyment upstairs, downstairs, inside your house and out. You will get the choice of three channels for optimum signal reception and tuning control on headphones. Frequency Modulation (FM) transmission resists static and distortion, for higher fidelity. Quartz-locked frequency synthesis transmission and reception is free from tuning drift, and eliminates the need for fine-tuning and distortion caused by mistuning. Switchable 15 kHz noise filter on the transmitter reduces noise at the TV horizontal scanning frequency. The filter can be switched on when the TV is on, off for all other times.30 mm diameter drive units are larger than many portable headphones for deeper bass, lower distortion and wider dynamic range while frequency response extends down to a low 20 Hz. These headphones provide 30-hour battery life (with optional alkaline batteries) that lets you listen again and again before replacing batteries. PET diaphragms ensure high rigidity for minimum distortion. Ferrite magnets combine high energy and small size, for ample sound output. Self-adjusting headband conforms precisely to the curve of your head for a fit that stays comfortable, even after listening for hours on end. The headphones feature Mute function that allows avoiding noise through the headphones and cuts out the sound when no audio signal is available. Automatic power switch for both the headphones and transmitter conserves battery life. When the transmitter senses an input signal, it turns on while the headphones turn on when you place them on your head. Single volume control in one earpiece conveniently adjusts the volume for both channels. These headphones are supplied with a connecting cord that goes to the headphone output of your high fidelity system, TV or VCR.