A vintage early motorcycle fuel cap. Has a flat top Listed as used as it has marks etc from decades of storage but possibly it used as gasket very good. It looks to be a very well engineered cap It has a small breather hole in the centre. It is Like 2 1/8” or just under inside Looks to be roughly 20 tpi thread but hard to see. Check photos for correct fitment to make and model. For restoration as not tested
