Old Man Hearing Aid Sound Amplifier Sound Collector, Red, Blue1. Material: ABS 2. Weight: 2. 7g (single) 3. Frequency response range: 300 4500Hz 4. Size: 2. 8x1. 4cm (single) 5. Range of use: hearing aids 6. Working voltage: DC 1. 5v 7. Working current: less than or equal to 4mA 8. Power supply mode: USB 9. Features: powerful chip, optimized noise reduction, mini stealth, stepless tuning 10. Packing list: packing box, storage box, manual, charger, cleaning brush, filter changer, screwdriver, silicone earplugs,