Warning Infusion Needle / blood taking needle

the infusion needle can't be used once being exposed to the air for few minutes.This design have done some- thing on the needle to make the color change gradually after the package being teared.After 2 to 3 minutes,the color will turn to red completely.This color warns that the needle can't be reused,to achieve the goals of using needls standardly and prevent if from reuse.