My son uses much gel packs that you put in the freezer. The shape and characteristics of this object we have encouraged al buy. For cold, I do not recommend it because it does not get very cold compared to gel compresses and thereby loses its ability to cool stiffly. It is against well studied in form as it maintains itself. I put 4 * for hot because it works correctly. Pay attention to timing in the microwave. I am a bit disappointed especially considering the price compared to gel compresses ... I have redeemed 5 gel packs ...
