Garmin mount rubber shims.

[Milzy]

Both my thinner rubber shims have vanished without a trace from my mounts. Where can I buy the correct ones from?

 

[Sterlo]

If it's the bit I think it is, you can get them from Ebay but you might have to buy a mount (usually only a few pounds)

 

[Pat "5mph"]

I used bits of an old inner.
Many years later, my mounts are still firmly fixed on all my bikes.