A miniature of a helm

[fernando]

Just acquired in a London arms fair.
I would call it a 1X2 scale as it measures 22 cms. in hight. I understand this is a tournament helm, but would like to know more about it, like: is this the reproduction of a specific known helm, exhibited in a museum or collection ?
Is the term "frog mouth" well attributed to this model ? Was it a fashion of the XV century?
Any comment will be so much appreciated. I am more interested in the chronicle of this device in its original version than in this miniature itself ... although i find it rather well made and appealing .

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