Boston Acoustics Reflection Series RS 230 Satellite/Bookshelf Speaker (Gloss Black, Each) (Discontinued by Manufacturer) 3.5 -inch Deep Channel Design (DCD) mid-bass driver delivers smooth, extended response 1-Inch (25mm) EWB (Extended Wide Bandwidth) tweeter delivers exceptional clear and detailed highs Elegant, scratch resistant high gloss piano black lacquer finish Magnetic grille minimizes acoustical interference for an improved soundstage Nominal 8-Ohm impedance and 87 dB sensitivity