OSS Limpet Mine question…

[digi-shots]

From what I understand limpet type mines were used in both WWI and WWII.  During WWII Britain had their own type of Limpet mine while the OSS developed one especially for the US.  The mine was developed with a series of magnets that would be attached to the hull of a ship and included a demolition charge.

 

Does anyone know when the OSS Limpet mine was declassified?

 

Thanks!

 

note…. There was an inert one on eBay recently and no, I was not the high bidder. (Sold for $891)

[WWIIBuff]

You didn't happen to save any pictures from the one that sold on Ebay that you could post, did you?  Was it the black "clam shell" type of limpet mine that used a Firing Device, Chemical, Delay?