This is a replacement keypad and button overlay for those worn out buttons on your indicator. With years of repeated use, it is not uncommon for the electrical contacts in the a button key to go bad. Generally it’s the Power Button or the Zero Key. Regardless, this is the replacement.
This keypad will say “Optima” but it will work for any of the indicators in this family. Please select LED (orange/red numbers) or LCD (black back-lit numbers), as they are different products.