Tattoo needles are used to inject ink into the skin as part of the tattooing process. They come in a variety of sizes and shapes, and each one is designated with a number. These numbers indicate the needle’s size, configuration, and shape. Different styles of tattooing require needles of different sizes and shapes, and understanding what the numbers mean can help you choose the right needle for the job. For example, the number 3 indicates a round shader needle, which is used for shading and creating soft edges of a tattoo. A 5 is a liner needle, which is used for outlines and tribal design work. A 7 is a magnum shader needle, which is used for wider shading and softening the outlines of a tattoo. A 9 is a round liner needle, which is best for outlining small, intricate details. As you can see, the different numbers allow you to choose the right needle for your specific style of tattooing.