Huskvarna 221rh

[Dcook11]

After removing fuel cap, there is a red piece that is removable. Can’t find what it is for.

 

[mechanic mark]

https://www.husqvarna.com/us/search-results/?groups=DOCUMENTS&q=221RH

 

[Scrubcadet10]

I believe i know what you're talking about.... it's just a gauge, you don't fill the gas up past the bottom of the red piece.
post a pic of it if you can.