Features: – Digital Voice & Sound Hearing Amplifier – Universal Fit Ear-Stud – Built-in Rechargeable Lithium Battery – Charges via the Included Charging Base Dock – Interchangeable Ear Tip to Seal Out the Noise – Selectable Listening Modes: Normal, Noisy Background) – Unique Ergonomic Design to Prevent Occlusion Effect – Circular Volume Adjustment Knob – Active Noise Reduction – Over Discharge/Charge Feature – Wider Dynamic Range Compression What’s in the Box: – Hearing Amplifier – (3) Ear Bud Tips – Charging Base Technical Specs: – Construction Material: ABS – Input Noise: =30dB – Sensitivity: =30dB – THD: 4% – Max Sound Output: 120±5dB – Frequency Range: 200-5000Hz – Power Supply: D.C.3.7-5V – Working Voltage: D.C.1.5V – Working Current: =4mA – Rechargeable Battery: 3.7V Lithium-ion, 15mAh, 0.0555Wh – Dimensions (L x W x H): 0.94’’ x 0.55’’ x 0.35’’ -inches