KEF R300 Bookshelf Loudspeaker - Walnut (Pair) The R300 features a 5 inch Uni-Q driver array, which consists of both mid-and-high-frequency drivers. The purpose of the array is to have both frequencies coming from the same place, allowing them to integrate perfectly and create a convincingly natural sound. The R300 bookshelf speaker also features a 6.5 inch low-frequency driver below the Uni-Q array, which ensures a clean, deep and uncompressed bass output with superb dynamics. Surrounding the Uni-Q driver array is our new mid-range Z-flex surround, which projects audio more efficiently into your listening space and results in undistorted high frequencies. The R300 affords you the option to use either a single amplifier as your source, or to bring in a second amplifier to handle certain frequencies. At just over 1 foot tall and 8 inches wide, the R300 is the perfect candidate for any bookshelf, desktop, or countertop in your home or office.