It is not currently possible to do so.
If you provide a feedback to support we should be able to look it up and tell you what model it is. DONT post the feedback here.
Alternativley you could determine it based on specs:
WG4000 = 4GB w/500GB harddrive -no RAID
WG4500 = 4GB w/300GB harddrive -RAID 1
WG5000 = 6GB
WG5500 = 12GB