Each speaker measures 36.2”H x 6.3”W x 9.2”D, without the small wooden plinth (about 9.25”W x 1”H x 9.5”D) that bolts to its underside.It has what B&W calls a Decoupled Double Dome 1” aluminum tweeter, newly developed for and used in all of the 680 S2 models. According to B&W, a ring is added to the tweeter’s dome to push the natural resonance of aluminum well beyond the audioband; usually, that resonance is at a frequency within or undesirably close to the range of human hearing. The entire tweeter assembly is decoupled from the cabinet with a special mounting system designed to avoid the transfer of resonances to it, or vice versa.Below the tweeter are two 5” Kevlar-cone drivers with rubber surrounds. One of the benefits of Kevlar is that it can stop a bullet -- something that’s obviously irrelevant when it comes to hi-fi. B&W uses it because, they say, it’s a choice material for “soaking up standing waves in a speaker cone.”Below the woofers is their version of a port, called a Flowport for the tiny dimples in its surface, which make it look like the surface of a golf ball and have the same function: to reduce air turbulence.Low on the rear panel are two pairs of binding posts, to facilitate biwiring or biamping. If, like me, you don’t want to go that route, the jumpers needed for single-wiring are already installed.------The Bowers & Wilkins 684 S2 is a floor-standing speaker system that has a 2.5-way design, an 8 ohm impedance, and a frequency range of 44 - 22000 Hz. It has a 0.98-in aluminum Nautilus tweeter driver, a 6.5-in woven Kevlar mid/woofer driver, and a 6.5-in woven Kevlar woofer driver. It has a width of 7.8 in, a height of 35.8 in, and a depth of 11.8 inFeatures150W maximum power handling. For robust sonic output.Two 5 woven Aramid fiber woofer cones. ...1 decoupled double-dome aluminum tweeter. ...Vented enclosure. ...Dual binding posts. ...72Hz - 22kHz frequency response (±3dB) ...87dB SPL sensitivity (2.83V, 1m) ...8 ohms nominal impedance (4 ohms minimum)