Features:Accurate and easy to useVolume can be adjusted with 4 levels.Help you hear the sound clearly and loudly， whether indoors or outdoors.Maximum loudness 130 +/- 5dB.Sensitivity: >= 50dB.Frequency range: 300Hz ~ 4000Hz. Package include:1 x Powertone F-138 In-Ear Hearing Ai1 x LR44 1.5v Battery3 x earplug1 x Manualsku��LY230