It might be worth your while checking the length of string required for your U-Bass, as these strings fell a tiny bit short for mine. What I mean by that is that on some of the strings, the part from the nut to the machinehead, the string isn't fully wound like the playing part of the string, it's thinner (presumably to help with tunage slipping), but the strings could do with another inch or two of the fully wound string part as it very nearly didn't fit mine. It wasn't until the strings were fully tuned up and settled that the fat part of the string was sitting on the nut. It almost didn't fit. That said, they did fit just about in the end.
In terms of sound, they sound like steel wound bass strings. If that's the sound you're looking for, this are definitely worth a go. Now that I've tried these strings on my U-Bass, I'm not going back to the rubbery strings.