This guide explains how importers, distributors, and fitness brands can evaluate the true quality of factories producing resistance tubes with handles. It breaks down the key factors that influence performance and durability, including material selection, extrusion precision, handle construction, and bonding methods. Readers learn what factory capabilities matter most, how to review QC processes, which certifications a reliable manufacturer should hold, and how to spot common production issues early. The article also provides a practical checklist for sample evaluation, a clear cost breakdown, and advice for building long-term partnerships with dependable suppliers. In short, it gives B2B buyers the knowledge to choose the right manufacturer, reduce product risk, and strengthen their supply chain.