1. Check surface by eye: if the surface looks very fine, means good. If the surface looks coarse, not good.
2. Check straightness: put on the side of a ruler, good needle looks very straight.
3. Check ductility by hand: fold the needle with a set angle, if break, means bad toughness, not good needle. If the needle resume to original and not break, it means it is good needle. This is the most important point to check the needle quality.
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