The Lithium-ion battery pack delivers up to 2X more operating time than standard batteries with no memory effect - recharge whenever feel like it. The battery charger is built-into the battery case with LED charge status indicator and automatic charge protection that stops charging when battery is completely full. Lightweight and powerful with Piezo microphone technology provides up to 40% longer battery life. Comfortable pistol grip and 3 modes: Talk, Siren and Whistle - Effective range up to one mile (1760 yards). Weatherproof high impact plastic and steel battery indicator light shows power status (low, med, hi) on the outer housing. Volume/gain knob inside the cover for more control over the sound. Shoulder strap. Half the weight and twice the battery run time of other megaphones. Easy to use battery cartridge, requires 8 C-cell batteries or optional S1405 rechargeable lithium-ion battery pack. Lasts up to 40 hours continuously on 8 C-cell batteries and 8 hours on S1450 rechargeable lithium-ion battery pack. Net weight 2.5 lbs without batteries.