Hello Fritz,
It's an S15, the so called Gottcho.
Lucian Gottscho originally designed this bayonet as an S14, but his design wasn't approved. In 1915 it was nevertheless accepted because there was a shortage of bayonets in the german army.
Less than 10.000 were produced only in 1915. The ones with the sawback are extremely rare...
The components of the S15 were produced by subcontractors. Assambling of the bayonets was done by Gottscho's company. That's why on the blade the markings of different makers are possible next to the Gottscho symbol...
Following producers of the blades can be found:
KS
KS D
SK
SM
BI
SW
S
WS
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