barb barbed barbed wire barbs border boundary devil's rope escape fence imprisoned oppression prison razor razor wire secure security sharp sky wire wires appearance barbed-tape barbed-wire barricade barrier danger double fencing gray grey injury metal protection razor-sharp razor-wire restraint security-fence silvery spirals strands twists warning blades fear military terrorism security fence sign wall barbwire clouds curl curve diagonal gate get off iron no access stay away stay out angle angles deteriorating light old protect protective rust rusting rusty texture textures caution cautionary-tape plastic plastic-tape tape