This is a fairly common material now. It's an attempt to match the supersmooth linear light output of neon tube without the fragility or expense. In many applications nothing will beat real neon, but for some environments like theatre or fairgrounds where the real thing would be too fragile it's an interesting alternative.

Here's a link to the UK listing I bought this from:
https://www.ebay.co.uk/itm/302169852307

And what appears to be the same sellers USA listing:
https://www.ebay.com/itm/292246704318

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