in ceiling or in wall speakers

In ceiling and in wall speakers.
In many cases for to have a better sonorization or because the situation needs to hide the speakers, the right choice is to install the in wall or in ceiling ones.
There are many types of them. Rounds, squares, rectangulars, motorized, available in many colors.
They can working with costant voltage up 100V or with low impedance 4/8 Ohm. It depends from the result it wants to obtain