Swapping out the Contemporaries that came on my NXT-5 with D-Addario Traditionals. The ball-end silk on a few of the holes was pretty snug but the string could be pulled through without drama or trauma. B, however, is no-go. The peg end was quite snug and none of the ball-end silk will fit. I can measure the silk and drill the hole bigger without issue, but if there's already a "right answer" for the appropriate size, I'd be glad to know it. If there isn't already one, I'll post my results tomorrow. I have or can get any size needed - "English fractional," number, letter. metric - whatever.