Seat post step down adapter

[WorkonSunday]

Hi all,
Just wondering if anyone has experience with using a smaller diameter seat post in a larger seat tube frame?
I have seen done on alloy commuter bikes with alloy seatpost but not seen it done on a more serious carbon road bike. Basically my frame takes 31.6mm seat post as standard but I want to use a 27.2mm seat post, will one of those eBay adaptor work? Thanks.

[Tifosiphil]

Yes, it will work completely fine. I would normally choose a branded one for accurate fit though and depending on seatpost length I would use one of the slightly longer ones such as the USE models

[1sanglier]

I confirm USE model work fine;

[Steve Curtis]

It's called a seatpost shim. They work fine but in my experience the plastic ones work better than metal.
USE are easy to find so go with that

[WorkonSunday]

Thanks all! USE it is then!