This is an Athena inner cylinder head dome.
It is a replacement part for their modular cylinder head system.
The size is 54.00mm.
If you have an Athena head and need a new dome, maybe you damaged the old one or you are changing your compression ratio, this is the part you need.
The manufacturer part number is S410485308002.
It is brand new, still in the packaging.
Please be aware of the California Prop 65 warning for this item.
It says it can expose you to chemicals known to cause cancer and birth defects.
That warning is on a lot of performance engine parts these days.
It is made by Athena, a well-known brand in the motorcycle and small engine performance world.
If you are building a high-performance engine, you know the drill.
This is a precision component for a precision setup.
