[drakelist] Drake W-4 vs Drake WV-4 Wattmeters

[Bill]

Hello,
 
I have a Drake W-4 wattmeter. I just saw someone with a WV-4 wattmeter.
 
Can someone please tell me the difference between the W-4 and WV-4 wattmeters?
 
Thanks!
 
73
Bill
K9BUB