Despite the many pictures being shown in the international media of a tall concrete wall, more than 97% of the planned 720 km. (480 mile) security fence will consist of a chain-link fence system. Less than 3% of the fence will be constructed of concrete. The short concrete sections are intended not only to stop terrorists from infiltrating, but also to block them from shooting at Israeli vehicles traveling on main highways
http://www.mfa.gov.il/mfa/go.asp?MFAH0o170