Airlines recommend hard-sided cases for durability.
航空公司推荐使用硬边的提箱以求耐用。
《柯林斯英汉双解大词典》
2
Spectators will be restricted to one bag per person and hard-sided hampers and cool-boxes will be banned for the first time.
届时观众每人只限随身携带一个包，硬边的食物篮和保温容器都将首次被禁止带入场内。
3
According to the TSA, "the passenger didn't have a little baggie with a goldfish in it, they had 4 large hard-sided suitcases each filled with only fish and water."