The Zem is a completely different approach to hearing protection which still enables you to hear conversations or range commands. The Zem units use patented "Sound chamber" technology to achieve an astounding NRR31DB noise reduction rating in a very small, lightweight and foldable unit. The really great feature is your ability to hear speech frequencies with great clarity while wearing the Zem. No muffs, batteries, electronics or control knobs. Made in the USA. Mfg: Sensgard