A terrific example with a superb FAR stamp.
I've never seen "SW" before but given that it runs under the grommet, I would suspect it is the manufacturer's logo.
I took a look at your F.A.R.44 ,Amazing ! Brothers in arms 8)
Same stamp same feldgrau ,our helmets must have met at the Somme ,coz that’s where the 44th was between 1916 and 19 17.( after that the steal helmet was introduced)