This is a rather rare survivor from the 1960s. It is a vintage toy called Boomerang Tennis - it is made of tin plate and is shaped a little like a doughnut - with a gold coloured indentaton in the top. The main body section is filled with weight so that it is heavy - and into the central dip - sits a little hard red plastic ball on a string.
I would imagine that you would originally have put this on table top and there with have been little bats - and you would hit the ball on the string back and forward. The string to stop you batting the ball over the room, but of course!
This old game (sadly the bats have long gone!) is in very good condition as you can see in my photographs - with no dents, nasty scratches or rusting to the tin plate - all the colours remain bright and fresh.
Certainly a quirky present for a tennis buff - would make a fun desk top paperweight.
Happy to post internationally - please ask me for a postage quote.