Treating Severe Vitamin B12 Deficiency B12 IM Injection Know Your Needles A Quick Nursing Guide! Today, let's understand the different types of needles and their clinical purposes Green Needle (21G) For IM injections like like, swipe, and save for when it's your turn to do an injection on a patient Intramuscular (IM) Angle: 90 Needle Size: 2225G, 11.5 inch Med Examples: Vaccines (e.g. Tdap, Self injecting vitamin B12. Quick and painless jabs after a B12 by Dr Caroline Palmer Medium