Energizer CR1632 3 volt lithium

My kitchen scale died mid-recipe and these little coins saved the day. Popped one in, and the display lit right up with no fiddling. They’re lighter than I expected, but the 3-volt punch is solid for a heart rate monitor too.

Finally found these for my car's keyless entry fob, and the battery hasn't died once since I put it in. The 3-volt lithium power keeps the signal strong every time I walk up to the car.

My heart rate monitor kept losing connection until I swapped in this battery—just popped it in and it synced perfectly. The 3-volt lithium was dead simple to install and the monitor's been rock steady for weeks now.