Replacement Oil Drain Plug

[KsGman]

I am doing the first oil change on my new (to me) 11 300ec and the hex head drain plug was nearly rounded out. When removing that plug, no gasket came out with the plug. There is a copper gasket pressed up into the case that does not appear to want to come out (easily).

The replacement plug I purchased from Matto came with a steel washer/gasket.

Wondering if anyone else has purchased this plug; is the steel ring a throw-away (assuming the copper washer in the bottom of the case looks good)?

Thanks.