quillg, i'll add what I know to the mix. Like Sage's reply said the B denotes the blank. In other words, if you find one marked LLB or RPLB, it's a custom built rod on the Sage blank. The GFL's were the less expensive versions of their counterparts. For instance, I have a 7wt RPL, GFL...it's the RPL blank, but it has cheaper hardware on it compared to the standard RPL. Hope that helps.