When installing peephole in your front door, first you should decide what height is comfortable for all members of your family. Then mark the middle of your door where you are going to drill the hole. Now, use a small drill bit to make a hole completely through the door. Then, switch the drill bit to the diameter indicated on the peephole box and drill halfway through the door on one side and switch to finish drilling through the door on the other side. Make sure the right side is facing out by looking through the peephole then position the two sections in the door and tighten. Use your screwdriver in the interior slots to finish tightening. Once your peephole is installed test it out and make sure your viewer is clean and ready to use.