Rubber grommets keep the loop of the tattoo needle bar snug with the armature bar, creating a more stable tattoo needle when the machine is running. Without a grommet, your tattoo needle will not be secure and will vibrate excessively, causing shaky outlines, unstable shading, and ink spitting from the tube tip. These rubber grommets absorb the vibration between the eye loop and armature bar, ensuring smooth, precise tattooing.