Good, inexpensive filters, I have been buying only them for more than a year. They often go on sale. I have never come across a defective cassette, before that I bought a Russian one, I will not write the name and for 4-5 cassettes I definitely came across a defective one, I do not know how they did it, but the water almost did not pass. The rat does not have such a sore. I take a handful, enough for 3 weeks.