Hey there, I just picked up a pair of nickel swing bass 66 strings, standard gauge at guitar center, the RN 66LD: http://www.guitarcenter.com/Rotosound-RN-66LD-Nickel-Swing-Bass-Strings-100190147-i1166963.gc Yet, on the Roto website, they do not have these listed, they only have the RS66LDN: http://www.amazon.com/Rotosound-RS66LDN-Nickel-Guitar-Strings/dp/B00240BI14/ref=sr_il_1_1?s=musical-instruments&ie=UTF8&qid=1359746319&sr=1-1&keywords=rotosound+66+nickel The difference in the 2 being the guitar center ones are 45-65-80-105 and the once listen on the roto website are 45-65-85-105. Does any one know what the story is here? Are they identical strings aside from the different A string? Just curious the story as to why the ones I got are not listed on the roto site. Thanks! Just a question for piece of mind.