F18 Pocket Model Hearing Aid Hearing Enhancer Ear Machine Sound Amplifier In The Ear Hearing Aid In The Ear Hearing Aid (White),Sound Enhancement For Old Age (18F) Pocket Model Hearing Aid (White),Sound Enhancement Wired Box F-18 Wire Pocket Model Hearing Aid (White, Green).Package included: 1 x F-18 Hearing aid 4 x Earplug (different sizes) 1 x AA battery 1 x User manual 1 x Box Note: Adjust volume to the minimum before wearing. Choose an earplug of slightly bigger size to avoid whistler. Increase volume gradually to avoid sudden increase in sound. If you hear a howling, check the ear (silica gel) is appropriate and whether the size of plug is tight, the appropriate choice of earplugs and plugged, make sure no air leakage. Keep the ear plug clean. Remove the battery if you don’t use it for long time.