Is this a LM Breather?

I have found this in amongst my stash of spares. Is it a Le Mans breather ? Now I’ve read about the flap thingy but haven’t really got a clue! Looking down the largest orifice there is some sort of something, is this it? If indeed this is the aforesaid breather!

Looks like that to me.

Just found a post in the search section after I found a way to look for Le Mans without using Le!Tells me most of what I want to know except if the thing down the hole is wanted or not.

It’s basically a large washer with a coil spring above it. I have got a new box to put on, only 'cause old one is thick with rust, but which will brush up with a coat of Hammerite, but still I have been using that with its stock valve plus a ball valve since 1987 with no probs whatsoever, so I’m leaving it that way. What I have noticed is the spring gets weaker with age, so makes it a bit easier to open. Where ‘flap’ valve came from I don’t know, stuck for describing it any other way I suppose!

So does this look like it should? Can I test it somehow?