These filters are in usable condition, and I have tested that each filter's front and rear threads screw into another filter without difficulty. I have not cleaned these filters, and they generally show some usage; some are mint and spotless but most have some dust, many have e.g. some scuffing and wear on the paint, however I will not sell a filter with obvious meaningful damage (see photos for a representative idea). They will be fine to use for appropriate applications after you clean them. The photos are of the stack at the time of listing, and as I sell and/or add more filters there will be filters not pictured and vice versa. They will have various weights and differing thicknesses. 

Satisfaction guaranteed. My goal here is what I view as a win-win: I'm offering these at a price that doesn't even really pay for my time, but I really would like these useful items to become useful again, as a kind of pushback against the cycle of excessive consumerism. You can get better polarizers for sure, but these are more than adequate for almost all purposes — I use one myself to make all my listing photos, for example. If you're not delighted with what you get, just let me know.