In the past I've made no attempts to hide or obscure serial numbers on my lenses when I put them up for sale. And I've always replied with the serial numbers when asked by a potential buyer. But now that I'm once again swapping some gear around and lenses are being sold, it occurred to me this may be a bad practice. On one hand I want sellers to be able to verify the general date of production from websites like http://www.photosynthesis.co.nz/nikon/serialno.html. But on the other hand I don't want to be opening myself to some unseen problems by revealing too much information to the public at large. So my fellow photo.net members, are there potential hazards are there in revealing the serial number? Is there any value to the serial number other than vague production dating? I should mention I take pictures of all my gear upon purchase, including pictures of serial numbers. I am aware technically someone could make a claim to the authorities of ownership if they know the serial number, but I'm confident I could prove rightful ownership in any court of law.