12 Week Steroid Injection Cycle Pack BD Needles, 2ml Syringes & Swabs B 12 (Methylcobalamin) Therapy MedClub by Dr Jenn Does size matter? Historically, a bigger needle gauge was considered better to prevent damage to red blood cells. However, our recent guidelines recommend using smaller gauge needles (2325 G) for all Purchase Needles (PrecisionGlide) 1 inch or 1 2inch at BiosenseClinic Know Your Needles A Quick Nursing Guide! , Today, lets understand the different types of needles and their clinical purposes , Green Needle (21G) For IM injections like vaccines or B12 vitamin Store Needle and Syringe Information for injecting vitamin B12 and vitamin C. Find out what needle sizes are recommended.