This needle cap may create a vacuum similar effect to control the airflow for an even amount of pigment and better result, for it has not enough air inside the cap. Too much air can force pigment down too much or to splatter, then only little pigment can get to the skin, which may waste pigment.
1. Environmental material is safe, non-toxic and harmless to your skin.
2. Can control the airflow for an even amount of pigment and better result.