1960 cab loaded with Univox "Pro-Mag" alnico Magnet 12" speakers. Are they any good?

[Sammy]

So I recently bought a cab and searched endless forums to find out what the hell are the speakers in my cab. While they don't have the blue tag on them, after comparing and looking at numbers, they are Univox "Pro-Mag" speakers. I have no idea what these are. Could someone please explain to me if they are good speakers and what tonal characteristics they have and maybe what other more known speakers their similar too.

Thank you

 

[GIBSON67]

Here's a pic I found on line. Look like a very beefy Alnico magnet and nice hefty cone. Dust cap looks stiff and probably cuts the highs somewhat, M2C.