This is an excellent polishing rubber wheel to bring the surface up to a fine finish.
These yellow silicone polishers are appropriately called "Miracle Gold Rubber Wheels"
They can be sourced from various suppliers, of which Dedeco is one of.
The product description on their website -
Ultra-fine – the “absolute best” silicone polishers for final polishing of gold. Eliminates the need for polishing paste!
In my experience these Miracles Wheels work well on all metals.