Tree frog pad is a rubber pad made up of eco friendly synthetic resin. The resin is sticky but does not leave any residue on the surface it comes in contact with. If the case become dirty or less adhesive then it can be cleaned only with water and little soap.
The case can withstand quick movements in automobile, boat and other places. The pad can be rolled which makes it convenient to carry. Costs 12.95 dollars. [link]