Klein Tools Cat. No. AESEM1S Earmuffs are engineered to incorporate both Situational Awareness and Bluetooth technologies for connectivity to surroundings and music. The dual-knob design featuring unique grooves for easy identification enables users to precisely adjust their Situational Awareness or Bluetooth volumes. Ergonomically designed vented headband provides cool comfort for all-day wear. These earmuffs charge in 2 hours, providing 25 hours of runtime. For more than 160 years, Klein Tools has manufactured premium-quality, professional-grade hand tools that deliver the performance, durability and precision needed to get the job done right. Our family of engineers, workers and craftsman continue to put six generations of expertise into every tool we create by using only the highest quality materials, superior workmanship, and keeping manufacturing as close to home as we can. Klein isnt just the name of our company, its also our family name. And since were an American company thats family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesnt just make great products, we make great products that stand up to the demands of the professionals who use them every day ... Since 1857.