All Series 4 audio cables are assembled by hand in Orlando, Florida. Series 4 Subwoofer Mono cables are designed to work in Low Frequency Effects (LFE) Subwoofer outputs of a pre-amp or receiver. Series 4 uses ultra-pure highly conductive oxygen free copper (HC-OFC) developed specifically for audio applications. Since stranded wire supports higher frequencies and cause distortion, Series 4 uses a single solid-gauge wire chosen to support low frequency bass signals. Tributaries Twin-Axial cable design has dedicated conductors with equal impedance for positive and negative signals. The signal conductors are wrapped with dual shielding to keep noise from reaching the single path. The Series 4 LFE Subwoofer provides a high performance bass cable that looks as good as it sounds.