These Internal Halyard Doors are unsurpassed in durability! This door comes with lock & keys and is meant for a pole with a butt diameter of 12" .If you are not sure of the butt diameter of your pole, take a flexible tape measure, wrap it around the base of you your pole. This will give you the circumference of your pole. Once you have this measurement, take that number & divide it by 3.14 or pi. That will give you the diameter of the pole.