Thank you for viewing. I purchased this at a physical store and used it only once in my ears. I have disinfected it with ethanol alcohol. Instruction manual included. Supervised by Dr. Nobuhiro Maruyama, Doctor of Medicine Mimi Care, a clear electrostatic removal earplug, authentic product. For those who understand used items, thank you. The following is an excerpt: ⇩ Due to the increase in electronic devices that come into direct contact with the human body, the human body is now more susceptible to static electricity than ever before. The ear (outer ear) is shaped like an antenna, and static electricity accumulates in the inner ear and the skull (such as the sinuses) around the outer ear. Mimi Care uses silicon, which is a semiconductor, so static electricity (electrons) gradually flows away. The static electricity (electrons) accumulated in the ear also flows towards the silicon earplugs, eliminating static electricity in the ear. However, if a certain amount of static electricity accumulates in the silicon, static electricity (electrons) will no longer flow from the ear to the silicon. To prevent this, two semiconductors with different directions are placed inside the left earplug, which has a high bioelectric potential, and one semiconductor is placed in the right earplug, so that static electricity (electrons) is eliminated or canceled out.