The is a Standard Receiver compatible with almost any G-style handset. It features a vandal resistant cover designed for long, durable use with payphone handsets. - DC Resistance at 20 degrees C : 145 ± 15 ohm - Frequency Response Range: 300-3400 Hz - Sensitivity: 100 ± 2 dB at 60mv - Impedance: 150 ± 30 ohm at 1 KHz - Weight: 60 grams - Dimension: (Ø) 45 x 22 mm