I posted this awhile back but never got a response. I took better pictures this time around in hopes someone may be able to help. I am wondering if this would have been used in WW2 and what they use something like this for? I understand it is for underwater communication but I am wondering specifically what this would be used for? Is there much value for an item like this? I purchased it at an estate sale about a year ago. All I know about it is the owner was a diver in the era of WW2. As you can see it is used and has some corrosion to it. It looks like it used to be grey and still has some of the grey paint but a lot of it is missing. It is also worth saying it is extremely heavy for the small size. On the outside it has a brass plate which reads "Navy Yard Number: 108-7588" Is it possible to find out where this was used? Also it says "Year purchased 1939, Cost: 732.00", is that right for cost? That seams like a lot of money in 1939? Help please?