Strapless high low black dress

Gift from my sister a few years back. I often used this at the cottage as a coverup because it was so light and airy. Very thin material but I wouldn't call it sheer. Strapless, but the very top and waist section are vey elastic-y so the dress doesn't slip at all! There are belt loops as well, but the dress did not come with a belt. Tag reads XS but could fit a size S as well as that is my typical size! From a smoke-free, pet-friendly (adopt, don't shop!) household.