Patented Dynamic Balance® The perfect material performance, eliminating driver and tweeter “artifacts” for more realistic sound reproduction at high and low volume levels. To install, simply mount the bracket and click the speaker into place then aim it and tighten it down. Speed Lock Mounting System Simply mount the bracket and click the speaker into place, Aim it and tighten it down. Outdoor speaker family Incorporate multiple Atrium speakers together to create the ultimate outdoor speaker system. Specifications Driver Complement 4 1/2″ (114mm) mineral filled Dynamic Balance® polymer cone, rubber surround, 3/4″ (19mm) anodized aluminum dome tweeter w/ rubber surround and neodymium motor structure Frequency Response 75Hz-25kHz Recommended Power 10-80W continuous Impedance Compatible w/ 8 Ohm outputs Efficiency (dB 1w/1m) 89dB Environmental ASTM D5894-UV Salt Standards Fog, Mil Standard 810 Immersion, Mil-Std 883 Method 1009.8 for salt and corrosion & Polk Audio Certification Cabinet material Mineral filled polypropylene Grille & Bracket powder coated material aluminum Hardware Brass or stainless steel Terminals Gold plated 5-way binding posts Mounting Options 180° Speed-Lock™ mounting Dimensions 8 5/8″ H x 5 11/16″ W x 6 11/16″ D (w/ bracket & knobs) (21.9cm H x 14.4cm W x 17cm D) Product Weight 1.63kg (each) Shipping Weight 4.1 kg (pair) Package Contents: Polk Audio Outdoor Speaker Atrium 4, White, 2pcs; x2 Mounting brackets; Manual.