Sorry about posting this, it has been covered I know but when I do a search for low B the engine won't give me anything because "B" is too short.I could not find a way around that. Anyway,I just go another 5 string bass (Atelier Z, love it!) and I don't know what strings are on there now . I don't know if it's the bass or the gauge of the low B but it sounds a lot better than the B on my other 5 string basses(Moon JB 5 and KSD Proto J) I am a Marcus Miller fan and of course play DR fatbeams. The gauge for the low B I currently use is .125. I don't have a caliper to measure the string on my Atelier Z with but it seems thicker.Maybe a .135. What gauge do you guys use? What are the pros and cons of thinner vs thicker B strings. I love the sound of Marcus Millers low D and I want to get that sound on a 5 string, but have not been able to. Maybe it's just the low tension of a tuned down E string that creates that funky D???