terry...i use spiderwire ultracast 30lb b/s moss green.(yellow and black box)
the diameter of the line is similar to 8lb mono.
You need the thickness of the line so that the current can tow it along to give the better presentation.
Braid also breaks well under the stated b/s so that is why you have to go up a couple of b/s strengths. Ie 10lb braid will break at around 6, 15 at 9, 20 at 15 and so on, as there is virtually no stretch factor as with most mono's.
There are also 2 types of braid, flat and round. Flat braids are made in the lower b/s, and they are not as good as the round braids in the higher b/s.
All braids at the hooks/rig end will eventually turn white after some use so you have to carry a marker pen to re-colour it on occassions.
I have used spiderwire of various types for around 12-15 years trying b/s of10 -15 - 20 - 30 - 40. 30lb b/s is the best
hope this helps