Hoya U-340 Filter on eBay - Does This Look Right?

[Andrew Dayer]

I noticed a US seller offering a range of items that they say came from a job lot from a US military lab, including an Edmunds Optics Hoya U340 50mm square x 2.5mm filter.

I don't have one and so am mildly interested but the seller's photo shows a peice of glass that has a degree of transparency in (presumably) visible light. The published internal transmittance graph for this item (SKU 46-440; https://www.edmundoptics.co.uk/document/download/353911) suggests to me that this glass should be pretty much black. But of course, I haven't seen one...

https://www.ebay.com/itm/114655695356

 

Is this likely to be a mis-label item or does U-340 actually look like that?

Thanks for any help

 

[colinbm]

U340 is essentially black.

[dabateman]

That looks like the piece of glass you remove when installing the U340 filter. Then the user slipped it into the U340 package to keep it safe. Said user than left the company or division and stuff got surplused and new owner has no idea what they have and go by the label.

That seems to happen a lot. That glass could be anything, including a more expensive Zeiss UV/IR blocker.

But you'll never know. 

Based on their other stuff and photos,  it looks like they buy storage units, not knowing what they get and resell the items.

[Andrew Dayer]

Thanks @colinbm & @dabateman. I'll pass on that filter (apologies for the weak pun).