Atrium4 is the smallest, most compact member of the latest generation of Atrium all-weather outdoor loudspeakers. Ideal for tight spaces, the Atrium4 will nonetheless prove more than capable of filling outdoor spaces with the legendary Polk sound. 11.43cm long-throw mineral-filled polypropylene cone driver with butyl rubber surround pumps out surprising bass response from a compact design. 19mm anodized aluminum dome tweeter with neodymium magnet for better power handling and smoother response. Broad coverage baffle design, adapted and applied from our current Atrium design but with subtle improvements in the new Atrium series. You want to fill a large open outdoor space with big, full-range sound, The new Atrium Series has a more steeply-angled baffle design that maximizes critical mid- and high-frequency dispersion over a large area, without sacrificing the detail. Polk all-weather certified, Atrium series speakers exceed baseline industrial and military specifications for environmental endurance (ASTM D5894-UV Salt Fog, Mil Standard 810 Immersion, Mil-Std 883 Method 1009.8 for salt and corrosion). With certification like this, your kitchen or bathroom installation is a cakewalk for Polk all-weather speakers.