This is a Platinum 52 mm MC (Multicoated?)- UV (Ultraviolet) filter in its case. I had never heard of Platinum filters, but seems they are fairly common.
I had dropped into a fairly small thrift store and the same two cameras as the month before were in the showcase. I didn’t want either of them so proceeded to the shelves to see if they had anything more interesting. The smoked plastic case seemed interesting, so I pried it open to see what it really held. It was labelled PLATINUM 52mm MC-UVF along the spine of the box, but I have been fooled before.
It has a very thin filter mount, one of the thinest I think I have ever held. The Platinum filters are available at BestBuy and Walmart. I haven’t found any negative reviews. I ended up with this one for $1.
I also had not come across "Platinum" branded filters. In doing a Google search I found reference to Walmart and BestBuy ... and also this blog ... which I find slightly confusing ....https://www.kentfaith.com/blog/article_who-makes-platinum-camera-lens-filters_15505