3M Optime I Gehoorbescherming - Universeel, Verstelbaar

Examining the ear piece it appears just thin plastic and foam, I don't know how item is engineered but I have to say it is effective in shielding high frequency noise but allowing low frequency so you can hear someone talking to you. I am very sensitive to powerful machine noise and high dBs, to prevent ear pain I have to wear defenders even just hoovering at home.