If you are comparing sihoo m57 vs m18, you are likely trying to find a budget office chair that still feels comfortable for long hours. I tested both chairs in my home office in the USA during work, video calls, and late-night browsing. Both chairs aim to give ergonomic support without the huge price of premium brands. But they feel very different once you sit in them every day. One feels more open and breathable. The other feels softer and more compact. After weeks of use, I