This is an all original vintage bayonet. I can not find any markings on it. I'm sure that someone will know and let me know what it is. The blade is 11" long and the mounting slot is 1 1/2" long. The button is flush with the handle and it has two pin holes as if you would need a small spanner wrench to release (unless it is stuck in that position). It is in excellent condition except for some minor blade rust pitting.