The Z bar for carpet is needed when you are transitioning from a carpeted floor to a hard floor such as hardwood. The Z bar will create a clean, finished look to your flooring. Consider installing this yourself and save money on a carpet installer. By doing this yourself, you will also be gaining experience in changing carpets and adding Z bars for future needs of your home.
Bring the carpet up to the point where the carpet will meet the hard floor and measure 1 extra inch of carpet over the hard floor.
Cut the padding underneath the carpet back to the point of where the hard floor starts.
Hammer the Z bar down by placing the tack bar on top of the edge of the Z bar and hammering the tack bar to the floor.
Fold the carpet over on the edge so that the extra inch of the carpet side is flipped under, and using your knee kicker, stretch the carpet to the Z bar teeth. Bring the carpet into the Z bar lip recession where you will see built-in gripper teeth.
Hammer down the top of the Z bar to grip and vice the carpet. You are now done with installation.