What battery for key fob?

I am away from the car/owners handbook at the moment, can anyone confirm the type of Battery required?

Thanks in advance.

If you have the key fob with you and if it’s keyless entry style they are super easy to open using the build in mechanical key like a screwdriver and check the Battery you need.

Battery type CR1632

What he done with the knife you can do with the key blade instead. 
Very smart design. 👍

Brilliant, Thanks Tony.

Been getting warnings for low key Battery for some time nowand I ordered some CR1632 from Amazon dispatched by Go green batteries and they arrived with expiry date 2032 👍🔋  

If anyone interested. 2 X Energizer Cr1632 3V Lthium Coin Cell Battery Dl1632 Car Keys Van Key Fob https://amzn.eu/d/0qJYte2 
 

Sometimes a Battery of similar size I have found work too. For my fob I think its 2032, when I didnt have any spare I tried 2025 it worked, slightly thinner. 

The cell in the Mk4's smartkey is a monster - CR2450!!  

Never had anything that needed a cell so big before!

3 hours ago, Mojo1010 said:

Sometimes a battery of similar size I have found work too. For my fob I think its 2032, when I didnt have any spare I tried 2025 it worked, slightly thinner. 

Also replaced mine with a CR2032 a few months ago works fine.

17 minutes ago, Cyker said:

The cell in the Mk4's smartkey is a monster - CR2450!!  

Never had anything that needed a cell so big before!

Lol, what a size 🫢 probably been designed as a power bank for jump starter when 12v Battery goes flat 🪫🙂