Speaker mounting brackets are designed to wall/ceiling mount bookshelf speakers, satellite speakers (some manufacturers include basic/integrated mounting hardware for their satellites), and rear surround effects speakers at the proper height. A good speaker mount should be able to securely hold your speaker, but also allow you some flexibility to direct sound effects to the sweet spot of your home theater room. Ideally, the tweeter on the front left speaker, center channel speaker, and front right speaker should each be located/aimed towards ear-level when seated for the best surround sound listening experience. But you usually get the most enveloping, room-filling surround effects when side / rear surrounds are mounted up above ear-level.