Conforms to EN352-2 H= 30 M = 24 L= 22 SNR= 28. PP-01-002 Made from a soft energy absorbing polymer foam which provides excellent hearing protection and all-day comfort. Slow recovery, low pressure foam conforms to the shape of the ear canal for enhanced comfort and wearability. Moisture-resistant – helps maintain a consistent expansion time, even in humid environments. Textured surface helps keep ear plugs in place. More information: https://www.greenham.com/3M-Workers-Choice