Uxcell Countersunk Plug Internal Hex Head Socket with Flange M22 x 1.5 Male 2Pcs

304 Stainless Steel for corrosion resistance, ductility at high temperatures, and low magnetic permeability.

It is a silver tone outer Hex Head Pipe Connector that is for closing and terminating the end of a pipe.

Great for blocking off intake manifold water ports, water pump ports, water temp and oil sender holes, engine block .
In order to enhance the sealing performance,you can use O rubber ring.