Using 145nm as the standard diameter for SP-D size (averaged from about 14 other “measurable” dodecamers from AFM), the diameters of multimers, hexamer, and trimers in this image are shown in “relative” size to that standard. I did just the dodecamers in the previous post but thought it would be nice to know the relatives sizes here, even though absolute dimensions in nm is not really available. (aside:  no one seems to put an accurate bar marker on their micrographs (self included) anyway, so a relative measure is probably the most informative anyway). The nice info here is that the multimer is significantly larger than the dodecamer which should NOT be if all the Ntermini are lumped in one central unit (something which i have doubted for a long time), but rather forming a small central ring with side to side links. The t-value is -3.31472. The p-value is .001071. The result is significant at p < .05.

Adding more observations will confirm or refute.