High-intensity light with attachment that allows peering into the ear canal to look for infection.
An otoscope is a flashlight with a special attachment for looking into the ear. With training, you can use an otoscope to help you decide if an ear infection is present. Inexpensive consumer-model otoscopes are available, but they do not illuminate the ear canal and eardrum as well as the one your doctor uses does. They can also be used as high-intensity penlights.