Don't know the code

Start from the kind of device you have. If the pack shows a code like CR2032 or AG13, check that label instead.

Remotes and key fobs

TV, soundbar, streaming, garage and fan remotes.

Make, model and year, then the key type.

Use the module number on the caseback. Many take CR2016 — not all.

Match the calibre stamped on the caseback.

For non-Eco-Drive quartz: match the calibre on the caseback.

Quartz only — solar and mechanical models are out of scope.

Jeweller numbers matched to silver-oxide codes. Alkaline lookalikes stay separate.

Diameter and height in millimetres. Last resort, when there is no code and no device page.