tactical vest
noun [ C ] uk/ˌtæk.tɪ.kəl ˈvest/ us/ˌtæk.tɪ.kəl ˈvest/
防弹背心
a piece of bulletproof clothing (= designed to prevent bullets going through it) worn on the top half of a soldier's or police officer's body to protect his or her chest and back