Garage door weather seal sold by the linear foot, so you order exactly how many feet you need. Select quantity 12 and you get 12 feet of seal, for example. Comes in 3-inch or 5-inch width. The width is how wide the flap is, not the length. The 3-inch works for smaller gaps and the 5-inch covers more ground if the gap between the door and the frame is bigger. Swap it out when the old stuff is cracked, flat, or letting in water and bugs. Measure your door's perimeter or the specific section you are replacing before ordering.