What product detail prevents the most return questions?

A small-shop question about size, material, care, color, and fit notes before checkout.

Return questions often come from details that were technically present but not explained at the decision point. Size tables, color photos, material names, and care icons do not always answer how the product will feel or fit in real use. For a local shop or small online store, what one product detail has prevented the most return or exchange questions: size caveat, material limit, color note, care condition, or use-case example?