Sonic Defenders™ protect your hearing - without stopping normal sounds and conversations. Safe sound levels are allowed through while harmful sounds (above 80dB) are reduced. This is done through a patented design that uses Hock's Noise Braker filter. When additional protection is needed, the protection can be reinforced by inserting the Sonic Defender's included "stopper" (this causes you to lose the ability to hear normal sounds and conversations). Made from an ultra-soft hypoallergenic material, together with the ergonomic fit, this means they stay in place in your ear comfortably even during long sessions. Thanks to their small size and fit in the ear, they can be worn together with a helmet or protective mask. They can be used together with a telephone. Each pair comes in a handy and protective tin. Features - 9dB Noise Reduction Rating (NRR) without stoppers; 16dB NRR with stoppers - Reduces potentially harmful sounds above 80dB - Lets normal sounds through - Made of soft medical grade hypo-allergenic polymer. - Ergonomic design for the snail to sit comfortably and securely in place even during long sessions. - Works together with a helmet, protective mask, phone, other headsets or supplementary earmuffs.