For me, two replacements.
First, my Thermapen, which replaced an anonymous Chinese clone which took forever to work out if my food was still frozen or overcooked.
Second, a new fish scaler to replace the almost identical one I had been using for almost twenty years until it died. The handle snapped off. I do eat a lot of fish and prefer to prepare it from scratch myself. I figure if the new one lasts another 20 years, it'll probably outlive me!