The earphones fit into the ear canals with either flanged soft plastic eartips or foam eartips. The plastic eartips can be cleaned and reused. The ER-4S have a wire design that manages the weight of the ears by a clip that attaches to the front of your shirt. It has a frequency response of 20 Hz to 16kHz, and a sensitivity of 108 dB at one volt input. To compensate for reduced sensitivity, ER-4S earphones can be used with a headphone amplifier when using low power portable devices.

Includes a review of the Shure and Etymotic In-Ear Monitors and the HeadRoom Portable Amplifier!