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control coupling
content coupling
common coupling
data coupling
external coupling
message coupling
There are many like flexible coupling, jaw coupling, sleeve coupling, tire coupling, pin and bush coupling, rigid coupling, etc
Bayonet Versus Bayonet - 1897 was released on:
USA: December 1897
transformer coupling
the top 'bayonet' appears to be ww2 Japanese rifle bayonet
the bottom 'bayonet' appears to be an early US 1903 bayonet or british bayonet.
message me with writting on bottom bayonet, on blade near top of hilt.........