This will depend on what your rifle has currently where the front sight attaches. If it's a gas block with a pic rail on top, it might be lower than the rail on the upper receiver and will need a specific front sight that is taller.
Can you post a good/clear picture of your rifle or even a stock photo from a website? That will let us know what setup you have.
You will need what is called a "Gas block height front site" These are taller to make up for the difference in height between the gas block and the receiver rail as T-Dogg described above.