✔️This ice crystal box contains dry ice crystal particles with coarse particles, good expansion and strong cold storage. ✔️After receiving the product, you need to add water yourself. After adding water, the ice crystal particles will swell, and after being expanded, they are frozen in a refrigerator for about 2-4 hours and can be taken out to use in a lunch bag or the like.< /p> ✔️Ice crystals will swell during water absorption and freezing, so do not add water when adding water, and you need to reserve a certain amount of space . ✔️ During the expansion process, if the ice crystal liquid overflows, it is non-toxic and can be used after cleaning. ✔️ Extra long cold storage , can be used repeatedly. Parameter: Product name: Ice cooling box Contains: granules of dry ice crystals Ice crystal box shell material: HDPE high density polyethylene Size: Approx 18.5cm12cm3.5cm /7.284.721.38 in. Usage: Use some water. Just add water once, can be used repeatedly. Scope of application: food