The brushes above are MS 24 (26 x 54), WW with a 24 MS 2 band knot measuring a little over 26 x 51 1/2
My experience with the 26 extra dense knot.
I purchased the extra dense 26 and sent it off to Bob at Elite who created a handle for it (I had Bob create the handle before I sent him the knot to take a 27 maybe 28). When Bob received the knot he back to me and stated that he could not put the knot into the handle because of the knots density it would require a 30 or larger opening, the handle could not be adapted to accommodate that size opening. I had him sent the knot and handle back to me. So at the moment I can't report on the quality of the extra dense 26 , accept that it,s a lot bigger then a 26.
I have a 24 which measures 26 for about 6 months and as everyone has stated these brushes are wonderful in every way, and for the price they are really spectacular. I had also purchased a 24 fan and had it installed in a WW Julie Rosette handle, great knot in a wonderful handle makes for a beautiful brush.