I (unfortunately) have no experience with birding or binoculars. But I have recently purchased a pair of vintage Nikons in what appear to me (a highly unskilled binocular-user) to be excellent condition. I have been reading everything I can find online to know more about my purchase, but am still in the dark. I was hoping that someone here could tell me what I have. They are inscribed with Nikon 9x 35 7.3* (degree symbol) and 724552. All I have been able to learn is what the 9x and 35 mean. I presume that the 6 digit number is a model or product number, but I can find nothing to help me figure this out. I have read about porroprisms and roof prisms, but nothing that tells me anything about these binoculars specifically. All I know is that they are a great pair of binoculars in hardly-used condition, but sadly without lens caps or case. Anyone out there have any information? I bought them to resell perhaps on eBay, but now I might just keep them! Thanks in advance for any info you can give this ignoramus!