Buying not one, but two Käsemann polarisers as replacements for two I thought I had lost on-loc, only to surprisingly find the "lost" ones way down in the second base layer of the camera bag a month or more later. That's more than $600 gone unnecessarily! I could sell them to recoup costs, of course, but given how precise and lavish these filters are I hold them in perpetuity "just in case". I am pleased to say I have not lost or misplaced any filter since April 2010.