Walkers Razor Rechargeable Muff (Black). Condition: Brand New in Original Packaging. Low noise/frequency tuned for natural sound clarify. 300 mAH (80 hours battery life). Full dynamic range HD speakers for clear balanced sound. Sound dampening composite housing. 3.5mm audio jack. USB charging cable included. The Razor Rechargeable earmuff features sound activated compression, frequency tuned for natural sound clarity, and full dynamic range HD speakers for clear balanced sound. What’s in the Box. Walkers Razor Rechargeable Muff. Audio jack: 3.5mm. Sound activated compression: Yes.