The Bowers & Wilkins CCM7.5 S2 is a two-way in-ceiling speaker with a smaller profile than the larger CCM7.3 S2. This speaker is designed to be more affordable than the CCM7.3 & also has a smaller footprint. This allows it to be put into ceiling cavities that have less space behind them or less area on the ceiling itself. This speaker features the same Carbon Dome tweeter that all the other CI700 speakers have as well as the Continuum cone for both the bass & mid-range frequencies. This speaker takes slightly less power than the CCM7.3 so would be useful in smaller systems with less powerful amplifiers. There is an optional backbox so if there isnt space for the backbox you dont need to use it. However if you do have the space the backbox will increase sound performance reduce bleed into neighbouring rooms & act as a fire break in case of fire. The technology employed in this speaker unit has been developed by some of the best acoustic engineers in the world. All their knowledge & experience can be heard throughout the entire CI700 range.