Rubber bungs in door frame

is it possible to still get the 3 rubber bungs that are in the door frame please and what are they for ?

I would also like to know the answer to this

Don't know if they're still available new, but there must be plenty in scrap cars. As for thier purpose, I was told years ago they were for  automatic seatbelts like used in the USA..

bungs are NLA now, but also used on the mk2 golf so not difficult to get replacements. and yes they are for the funky US seatbelts