A 9RS tattoo cartridge refers to a round shader cartridge with 9 needles arranged in a circular configuration. The "RS" in the name stands for "round shader," which is a type of tattoo needle that is used for shading and filling in larger areas of a tattoo design. The number 9 indicates the number of needles in the cartridge, with a higher number of needles generally being used for larger areas of shading. The 9RS cartridge is a popular choice for shading and blending in medium to large areas of a tattoo design, and it can be used on various parts of the body. It is important for tattoo artists to choose the appropriate needle configuration and size based on the design and area of the body being tattooed to achieve the desired results