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