Walker&#39;s Game Ear Archers Ear Digital HD Hearing Enhancer Top of the Line GSM Product Sound reducing Ear Muff Walker's Game Ear ES II BTE Digital HD GWP-WGEHD-AE Ear Muff First enhancement unit specifically designed for bow hunters Adjustable frequency tuning - bass/tremble fine tuning One channel/ One mode/ 7x enhancement, power 48dB. Sound activated compression. #13 battery for longest life