I just bought this thing. It is made of metal. It is about 10" long. Base threads into top. Base Has a threaded hole in the bottom about 3/4 of an inch. Marked B-S on the fin. I don't know if its military. Just thought somebody here would know. Maybe its for training? Thanks for your help.
Here is a link to the pictures
http://www.etsy.com/transaction/68950839
Here is a link to the pictures
http://www.etsy.com/transaction/68950839