24dB Noise Reduction Rating (NRR) with filter caps inserted * Lowers potentially dangerous noise levels above 85dB * Hear safe sound levels (with filter caps out) as if you weren"t wearing ear plugs * Metal-infused-polymer construction for detection by industrial scanners; bright blue in color for easy visual detection * Ear Lock by SureFire retention ring utilizes seven contact points to lock earpiece in place and fit the same way every time