I do not recommend brands, only cushions that I have tried. After going through countless pitfalls, I chose a cheap ice pad as the most suitable cushion, rather than a so-called high-end brand. Everyone's needs are different, especially for things like cushions that are used for a long time. A little difference will lead to a big difference in needs. You must choose according to your own situation. The expensive one may not be suitable for you, and the cheap one may not be impractical. I use an ice pad myself, but I feel that in your case you don’t need to cool down, you just think the stool is too hard. In this case, it is best to choose a simple soft cushion. It does not need to be particularly expensive, as long as the stool is softer. A few, and you'll feel much better. This kind of seat cushion is fixed and has a backrest. It is soft, but it is quite hot when you sit on it: Wuzhenju one-piece seat cushion and one-piece thickened one-piece chair cushion, back cushion and seat cushion. It costs 39.00 to buy on Jingdong and get red envelopes. This one is also available. There are two straps, which can be tied to the chair: Gongxun thickened cushions, office chair cushions, student stools, butt cushions, tatami mats, JD.com? 9.90 to buy. As for the brand, air fiber can also solve the problem of the chair being too hard. It’s just that the price is on the high side: Pineapple Zebra Summer Breathable Japanese Black Technology 4D Air Fiber Cushion Bird’s Nest Zebra JD.com? 458.00 to buy. The above three are soft and hot. The chairs in the dormitory are too hard, so you can choose this kind. If the questioner also feels that the stool is not only hard, but also stuffy and hot, you can refer to my experience in choosing cushions: What kind of cushion is better to buy if your butt hurts after sitting for a long time?