Just curious if anyone knows what these are....

They have green threading at the ball end.

The string is really smooth. You can't feel the windings.

Thanks.

Here's a pic.http://www.talkbass.com/forum/attachment.php?s=&postid=826731

You can see it better on the E and A strings at the headstock.

Could be Fenders. Fender 9050 flatwounds are very smooth, and have green silk at the ball end. Pyramid flatwounds have green silk at both ends.