VITAMIN B12 (Generic) Injectable Solution, 1000 mcg mL, 100 mL vial Easy Refills Chewy Rx B12 Shots Needle Size 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 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 Syringe and Needle Selection Guide by Burt Cancaster