what is the impedance of vmps mini towers?

Hello, I've bought a used pair of vmps mini towers and want to use it with tube amp. Does anybody know the impedance of the speakers so I can connect correctly?
Mini towers?.....most of the VMPS speaker line, is rated at 4 ohm.

I have a pair of VMPS Mini Tower II A's with all of the upgraded drivers. Rated at 8ohms. BTW, these are awesome speakers!
Hope this helps!