This shoulder rest is for a fullsize violin.   The brand is KUN, made in Canada, one of the best shoulder rests on the market. (I use a Kun myself.) 

This one has legs that fold inwards making it easier to fit into a violin case. 

The shoulder rest shows no signs of use.  They retail, new, for around £40.

If you were to buy a violin from me at the same time, I would refund the postage charge on the shoulder rest.