The In Phase XTB-828R is a passive radiator equipped active sealed subwoofer enclosure, designed to deliver low frequencies and true bass accuracy. It features an all-weather glass fibre woven cone 20cm (8") drive unit, paired with a passive radiator in a sealed enclosure for deep and controlled bass. The built-in 400W Class D amplifier offers high power handling and numerous controls, including high and low-level inputs compatible with aftermarket and OEM head units. This compact, "FOUR-in-one" enclosure reduces overall dimensions while providing great bass output. It comes complete with a wiring kit, but RCA cables are required if fitting to an aftermarket head unit. A passive radiator enhances bass response by utilizing trapped sound pressure to create resonance, similar to ported enclosures but without the downsides, resulting in better sound quality, a linear frequency response, and higher output in a smaller size. The Class D amplifier is robust, compact, and efficient, providing up to 400W peak and 200W RMS power. The superior glass fibre subwoofer cone is lightweight, durable, and rigid for optimal sound quality. Technical specifications include RCA Input Sensitivity 0.2-6V, High Level Input Sensitivity 1V, Remote Phase Switch 0-180 Degrees, Bass Boost 0dB~+12dB, Subsonic Filter 20-Hz-50Hz, LPF 50-150Hz, T.H.D 88dB, Fuse Rating 25A, Impedance 4 ohms, Dimensions 248x255x250 (MM), and Weight: 8kg.