“防御物”的英语？

他必须在顶上多加些沙土作为防御物.He must pile more sand on top as a shield.他们在州的南部铸造堡垒和其他防御物.They built forts and other defensive positions across the southern parts part of the state.肯恩视力, 然后点火, 取出后面的正确轮胎和秃鹰机器的防御物.Ken sights, then fire...