These strings sound phenomenal on the epiphone thunderbird vintage pro I (accidentally) bought on ebay a few weeks ago. I asked the seller what the strings were but he says he never changed them so thinks they were the original ones - I'm sure they're not the original factory set as those wouldn't have had silks and would have a nickel sheen to them that these don't.
These have red silks at the head end, but no silks at the bridge end. The ball ends are E-red A-blue D-white and G- red(again)
I've not used roundwounds for almost 20 years but these are perfect for this bass, so it would be worth getting a spare set if I can identify them.
The colour of the ball ends suggests they are rotosounds, and the red silks suggests swing bass, however I'm not 100% sure as I thought rotosounds would have red silks at the bridge end as well.
Any ideas?