The Czech hedgehog (Czech:rozsocháč) or ježek, is a static anti-tank obstacle defense made of metal angle or I-beams (that is, lengths with an L- or H- shaped cross section.) The hedgehog is very effective in keeping tanks from getting through a line of defense. It maintains its function even when tipped over by a nearby explosion. Although it may provide some scant cover for infantry, infantry forces are generally much less effective against fortified defensive positions than mechanized units.