What is like I said in my previous comment here, the era categories are absolutely ESSENTIAL for me to find vintage Christmas lights from the correct era – I stay away from anything made after 1997 (or so), as they are virtually all made cheaply in China! I'm often looking for vintage Christmas light strings with braided cords on eBay, even though the era categories weren't the best – I personally would have the following era categories: "Antique: Before 1946" [this is the era of cloth braided cord Christmas light strings with bakelite light sockets and bakelite male and female electrical plugs], "Vintage: 1946 to 1969" [this is the era of plastic braided cord Christmas light strings with bakelite light sockets and (usually, but not always) bakelite male and female electrical plugs], "Retro/Modern Vintage: 1970 to 1997" (or "Retro/Modern Vintage: 1970 to 1999") [this is the early zipline plastic cord era of Christmas light strings with (usually, but not always) plastic light sockets and (always) plastic male and female electrical plugs, when they were mostly made in North America/Europe/Australia/New Zealand as opposed to East Asia/Southeast Asia – notably China], and "Modern/Contemporary: 1998 to Now" (or Modern/Contemporary: 2000 to Now") [this the later zipline plastic cord era of Christmas light strings with plastic light sockets and plastic male and female plugs, where virtually everything is made very cheaply in China or – what is far, far, FAR less frequently – The Philippines]. Now, don't you get me emotionally started on the era categories (or the lack thereof) of extension cords, electrical timers, electrical power bars/outlet strips, electrical wall taps/wall blocks, and surge protectors on eBay...
