No serious track-side tuner is without one of these in their laptop bag.  Protects the hood/roof of the car and elps prevent the tragedy of seeing your precious laptop slide off of the waxed surface onto the cruel asphalt below.  12-inches by 18-inches gives you more than adequate space for your laptop yet ensures this rolls up and stows inside your computer bag.  Rubberized material is very resistant to automotive chemicals and can be easily cleaned if necessary.