tóngqiángtiěbì
ㄊㄨㄥˊ ㄑㄧㄤˊ ㄊㄧㄝˇ ㄅㄧˋ
Simplified 铜墙铁壁
Taivo → Settings → Partner inbox → Make the link. It stays in this browser.
Keep 銅牆鐵壁 and it comes back until you know it.