Battery Free Hearing Protection with Switchable Noise ModesThe Safariland TCI Foam Impulse Hearing Protection uses patented filter technology to reduce harmful noise while still allowing speech and audio to be heard. A soft memory foam tip and removable neck cord add comfort and security while switchable Impulse Mode and Full-Block Mode provide flexible hearing protection without batteries. Patented filter technology Allows speech and audio awareness Soft memory foam tip Switches between two protection modes No batteries required