Peltor Indoor/Outdoor Range Hearing Protection Ear Plugs 97079 are hearing protection designed for use at indoor and outdoor shooting ranges by the US Army and NATO. These Ear Plugs by PELTOR feature patented technology that provide two types of protection. When the olive end of the Earplug is inserted, a constant Noise Reduction Rating (NRR) of 22 decibels (dB) is provided. This is especially suited to all high-level noise and reverberation such as in an indoor range. When the yellow end of the Ear-Plug is inserted, the patented filter takes over to provide variable level protection for impulse noises without blocking normal communications such as range commands. This gives the Peltor Ear Plug a Noise Reduction Rating (NRR) of 0 to 22 decibels (dB) which is best suited in outdoor ranges. These features make Peltor Indoor/Outdoor Range Ear Plugs 97079 versatile hearing protection that are great for any type of shooting range.