Under the drivers seat of my 2004 #7 e-bay Prius the carpet has been cut on three sides to form a flap. Under the flap there seems to be a bolt head. My questions: 1. Do all Priuses (Prrii??) have this? or was this done by the dealer etc. 2. Why is it there? Obviously it must be something that needed to be adjusted after the carpet was installed. What is it? (Very curious) Tickwood