I believe you are right. It was either that, or Volcano, I can't remember...Pro Tech was a line of speakers started by PJ's Auto Sound in Erie Pa. They were in many of PJ's world championship cars in the 90's. I may be wrong but I was told once they were made to spec by the same manufacture as Atomic speakers.
round here they are full of really nice stuffs, not a lot of audio, but occasional screamers (i saw a $4000 pair of klipsh speakers go for $24 !!, i didnt get em but if i was there 5 minutes earlier!!!), and lots of other non audio stuff that is high value but very low cost.my local thrift stores NEVER have anything cool like old-school audio!