How Needle Gauge Affects Injection Comfort & Efficacy Needle Sizes Explained: Choosing the Right Gauge for Different Injections Needle Sizes Explained: Choosing the Right Gauge for Different Injections B12 vitamin Store Needle and Syringe Information for injecting vitamin B12 and vitamin C. Find out what needle sizes are recommended. Is this the right size needle for im injections? : r B12_Deficiency 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