ISO 6009:2016 establishes a colour code for the identification of single-use hypodermic needles of designated metric sizein the range of 0,18 mm (34 Gauge) to 3,4 mm (10 Gauge) . It applies to regular-walled, thin-walled, extra-thin-walled and ultra-thin walled needles, and to opaque and translucent colours.
It is not applicable to pen-needles.