 Right, yeah, an exterior walk-through door, yep. The first thing I would check is to make sure the door is perfectly hung. And by that, I mean it has an even reveal, top, side, bottom. And then looking under the door, sometimes with a flashlight, you can see gaps. So if you use a flashlight at the saddle, you can shine it on one side and look underneath and see if there's any gaps there. The type of weatherstripping you have is the kind that kind of looks like what's on a refrigerator door.