The Sony SS-E 21 is a bookshelf speaker that was designed to deliver a balanced audio performance suitable for a variety of listening environments. It features a 3-way speaker design, which includes a 12 cm woofer, a 10 cm mid-range driver, and a 2.5 cm tweeter. This combination allows for an extended frequency response and a rich sound profile. The speaker is known for its ability to handle a range of genres, providing detail in both highs and lows. The cabinet is constructed from particle board and is designed to minimize distortion, while the exterior finish lends it an appealing aesthetic. The speakers are rated with a power handling capability of approximately 100 Watts, with an impedance of 8 ohms, making them compatible with a wide variety of amplifiers and receivers. The sensitivity rating of 90 dB indicates that they can produce a substantial volume level from a moderate input power.