When selecting a camera firmware, it is important to note
that many camera models are just variations of their physical
configurations. The same firmware, based upon only one of 
the camera numbers, is used for all of them. The examples
below are just a few:

WV-SP509_xxx.zip is used for the WV-SF539, WV-sf538/549
     WV-SF548, WV-SP509, and WV-SW559/558

WV-SW175_xxx.zip is used for the WV-SW175, WV-SW172
     WV-ST165,and WV-ST162

WV-SFV631l_xxx.zip is used for the WV-SFV631L/SFV611L,
     WV-SFV631LT, WV-SFN631L/SFN611L, SFR631L/SFR611L
     and WV-SPN631/SPN611