This compact tester measures the energy remaining in a hearing aid battery (all sizes # 10, # 312, # 13 or # 675)

This tester does not require batteries to operate. Simply drop the battery with the positive side on top and gently push the battery on the metal bar and the display will show the percentage of energy remaining in the battery. A drawer under the tester keeps 2 replacement batteries if needed. A small chain allows you to keep the tester with you at all times wherever you are.