They're most definitely filters and they're barely used. No rust or corrosion at all. Coincidentally around the same time I found those I won an auction on eBay for a 1/2" Parker filter/reg, but these will come in handy... Some day... I think...
It's funny because I had been looking for a 1/2" filter/reg for about a month now and the same time I find the 3 filters in the garbage, I win the auction. Why can't stuff like this happen when I play the lotto?