Not only do the newest double door, swing panel traps catch critters coming or going from either direction, because of internal doors they will easily flush mount against a vertical opening. Just yesterday I had a squirrel job where the squirrels had chewed the weather stripping under a door. It took little more than seconds to set up. I just set the traps and placed them on the floor up against the door over the opening, done! With recessed doors, there was no blocking, no fabricating and no accessories needed. As quick as the traps were set on the floor, the job was complete, nothing simpler. Today a pair of squirrels were waiting to be picked up.