ER•4P (Portable) earphones can be used with portable CD, MP3, DVD and other players without requiring an additional amplifier. As compared to the ER•4S, the ER•4P has 10 dB greater output at high frequencies and 13 dB greater output at low frequencies. The higher sensitivity and enhanced bass of the ER•4P have made it the most popular earphone for most uses.

Includes

• ER•4 MicroPro earphones
• 5 ft. cord with 3.5 mm stereo phone plug
• 1/4" stereo phone adapter plug
• Six 3-flange ear tips
• 10 foam ear tips
• Filter changing tool
• 4 replacement filters
• Shirt clip
• Carrying pouch
• Storage box

Specifications

• Frequency response: 20 Hz to 16 kHz ±4 dB
• Acoustic polarity: + electrical = + acoustic
• Transducer type: dynamic 1 kHz sensitivity (ER•4B/ER•4S): 108 dB SPL for a 1.0 volt input
• 1 kHz sensitivity (ER•4P): 108 dB SPL for a .25v input
• Impedance (ER•4B/ER•4S): 100 Ohms nominal
• Impedance (ER•4P): 27 Ohms nominal
• Maximum output: 122 dB SPL
• Maximum continuous input (ER•4B/ER•4S): 3.0 Vrms
• Maximum continuous input (ER•4P): .75 Vrms
• Weight: less than 30 grams.