This waist trimmer belt is a one size fits all and it does go to a pretty large size. It holds up very well! It fits accordingly to how you wrap it. I have had no issues with belt rolling up or coming off but it does crease though.
When I wore it, I was really sweating at the waist. I also felt hot with it even though I wore it above my clothes.
I normally wrap mine starting with my lower section then bring it up over my upper section so my entire stomach is covered.
The material is finer than I expected but is stretchy and hand washable. It is good for daily use under clothes though. It does improve the posture. You’ll also increase thermal activity and perspiration which in turn will help reduce some inches. For the first few days, I only wore it for a few hours as recommended when you start waist training. Now I wear it for more hours a day!