Bowers & Wilkins CCM663RD Ceiling Speaker Pair RD stands for Reduced Depth so this speaker will fit into tighter spaces than the standard CCM663. A Shallower cone and redesign of the QuickDogs frame reduce depth to a more usable 92mm. While retaining everything that makes the CCM663 such as a great in-ceiling speaker. The familiar, yet discreet, dark blue Aramid Fibre cone of the bass/midrange driver delivers a stunningly clean, detailed response. Combined with the pivoting aluminium dome tweeter for adjustable off-axis treble response and three position EQ, make this one of the most versatile custom speakers around. Specifications Description 2-way in-ceiling system Drive Units 1x Ø25mm (1 in) Nautilus™ swirl loaded aluminium dome tweeter 1x Ø150mm (6 in) blue Aramid Fibre cone bass/midrange Frequency range (-6dB) 35Hz – 50kHz Recommended Amplifier Power 25W – 100W Sensitivity 86dB (2.83V, 1m) Nominal Impedance 8Ω (4.8Ω minimum) Frame Ø240mm (9.4 in) Cut-out Ø202mm (8 in) Depth behind surface 92mm (3.6 in) Protrusion 7mm (0.3 in) Net weight 2.3kg (5 lb) Pre-mount Kit PMK C6 Back Box BB6W or BB125C Bowers & Wilkins CCM663RD Ceiling Speaker Pair, Bowers Wilkins CCM663RD Ceiling Speaker Pair