ACX CS 4" Series Column Speaker Easy to Use, Traditionally Stable, Economical and Durable It is ultra-compact size allows the entire system to run efficiently and provides a simple yet effective solution for a variety of fixed sound reinforcement installation systems. Aluminum-magnesium alloy-based body, implanted with 4″ woofer along with 3″ and 4″ aluminium driver, bring out a stylish and magnificent appearance. Unlike regular speaker designs, CS selection of the aluminium driver maximizes, its performance on wonderful sound quality and smooth treble. It is excellent in medium-sized application.