Net Yaroze - composite ports covers

So, while browsing ebay the other day, I came across this picture:

I've been looking at pictures of Net Yarozes for at least 15 years and this is the first time I see those (plastic? rubber?) "covers" in the composite ports.

Were these commonly shipped with all Net Yaroze consoles?
How about retail (ie. consumer) units?
Or is it just something this seller added here? (maybe from a different Sony product)

 

I once had a brand new yaroze and it did not come with those as far as I remember.
No clue never seen them before!

 

Me too, mine didn't come with those.

 

those look live the AV port cover often seen on old SONY video camera and etc.

 

I bought my Net Yaroze from the UK SCEE in 1999, it didn't come with those

 

Retail units didn't have that thing too