Disposable needle, needle have serial number?

Q: disposable needles have serial number? The needle is thick or thin?
A: disposable needles in large batch number on the outer packing, only a single needle only size model, the average adult drip with black needle 7 and a half, children with purple needle number 5 and a half, with blood transfusion needle 9 and a half is yellow, this a few is a common, there are other models.
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