maybe it is just "防弹衣"?

送交者: ping_max 于 2006-11-03, 16:47:51:

回答: 警服后边写“police”没什么问题由 Jingzhang2 于 2006-11-03, 16:25:16:

as the guy mentioned in his first sentense.

I also agree that I don't see a problem if there are both Chinese and English, but the article seems to emphasize it is "只写英文"