The R-51PM powered speakers use a highly efficient, powerful yet minimalist design that engulfs listeners in their favorite movies and music. With a built-in amplifier, a multitude of inputs and Bluetooth® connectivity, the R-51PM is the most versatile stereo speaker system on the planet. Features: Built-in All-Digital Amplifier. 1" Aluminum LTS tweeters. 90x90 Square Tractrix Horns. Dual 5.25" Spun-Copper IMG Woofers. Bass-Reflex via Rear-Firing Port. Strong, Flexible Removable Magnetic Grille. Dimensions: 13.3" x 7" x 8.5".